All language subtitles for Unearthed Series 7 Special Seven Wonders of America Part 1 1080p

Narrator:
The golden gate bridge,

The washington monument,

The empire state building --

These and four
other engineering marvels

Are regarded by many
as the wonders of america.

Seven iconic modern-day
mega-structures

Set the benchmark
for american ingenuity.

How were they built?

And what secrets
do they conceal?

Today, investigators
use hidden records...

It's a monumental project 'cause
it hadn't been done before.

Narrator: ...And dynamite...

That's how you break it up good.

Narrator:
...To decode the mysteries

Of america's world-famous icons.

Across the united states,

These massive monuments
define a nation's identity.

How do engineers overcome
the incredible challenges

Of building bigger than ever
before in untamed landscapes

And in the heart
of great cities?

We reveal how the most powerful
nation on earth

Enters a new age
of engineering achievement

To build the seven
modern wonders of america.

♪

The seven wonders
of the ancient world

Span three continents

And thousands of years
of history.

But today, a new generation
of engineering wonders

Rises to take their place.

How does the united states alone

Match the engineering might
of the entire ancient world

Across a new
and untamed continent?

The national mall
in washington, d.C.,

Is america's
most visited national park.

It's also the home
of some of the country's

Greatest monuments.

At one end, the lincoln memorial

Honors one of the great
american presidents,

A gigantic seated statue

Inspired by an original
ancient wonder in greece,

The great statue of zeus
at olympia.

At the other end, congress meets
in the united states capitol.

And on the northern side,

The world-famous home
of the u.S. President,

The white house.

All of these monuments
copy the grand architecture

Of the classical world...

...With their elegant columns
and pediments.

The most extraordinary
stands proudly

In the center of the mall,

The first modern wonder
of america --

The washington monument.

In 1836, america's capital
is growing fast.

The people of the city
want to build a memorial

To their founding father

And first president,
george washington.

The ambitious plan
is to ship in stones

From all over
the united states...

And assemble them into
an audaciously thin stone tower.

This tower will be the
tallest structure ever built.

But the design is nothing
like the classical architecture

Found elsewhere
on the national mall.

What inspires the strange shape
of this modern wonder?

In the early 19th century,

Investigators discover
the remains

Of two gigantic ancient obelisks
in alexandria, egypt.

They excavate one
which has fallen

And is buried under centuries
of sand and debris.

Each stands nearly 70 feet tall
and weighs almost 200 tons.

They're carved from red granite

And are decorated with ancient
hieroglyphs on all four sides.

These incredible obelisks
inspire the shape

Of the washington monument.

But why do the people of d.C.
Choose an egyptian-style design?

A clue lies in egypt.

The temple of karnak near luxor

Once boasts
at least 13 obelisks...

Including some of
the most impressive ever raised.

The tallest
is over 118 feet high.

Today, in the center of
the temple, only two remain.

But the obelisks
don't disappear.

They're looted.

In ancient times, the romans
ransack egyptian temples

And ship obelisks
all over the world...

To constantinople,
now istanbul...

And to rome.

At 105 feet tall,

It's the largest ancient obelisk
in the world.

The romans fill their city
with eight large

And 42 small egyptian obelisks.

The desire for these
ancient monoliths

Continues into the 19th century,

Only 15 years
before the people of washington

Design their monument.

Other great modern cities

Start to raise
their own egyptian obelisks.

One is shipped to paris

And re-erected
in the place de la concorde.

A second is placed in london
beside the thames.

And the last is raised
in new york's central park.

Here they still stand...

Symbols of great power

Connecting these
modern metropolises

With the majesty
of the ancient world.

The people of washington want
to join this exclusive club

By building their own obelisk.

But they go one step further.

This obelisk
will outdo them all.

In 1848, this will be the
tallest structure ever built.

In six years, the monument rises
more than 160 feet

Above its foundations.

But in 1861, the country
plunges into civil war.

Work grinds to a halt.

The project kick-starts
20 years later,

When lieutenant colonel
thomas lincoln casey takes over.

When he arrives to inspect
the site, he's in for a shock.

The tower isn't even
a third of its planned height.

It sinks more than three feet
into the ground

And leans to one side.

Casey unearths
the foundations of the tower

And remove soil on one side
to straighten the monument.

Then he digs a series of tunnels

Down to a firm layer of clay

And fills them with concrete.

From these new foundations,

He then constructs buttresses
up to the base of the tower.

Then he can start building up.

And 36 years after work began,

The washington monument
finally reaches its full height.

Thanks to casey's work,

The washington monument
is a solid success.

By 1888, around 55,000 people
scale it every month

To proudly stand on the
tallest structure in the world.

The washington monument climbs
far above the ancient obelisks

That inspire its design

And sets a precedent for the
new world wonders that follow.

But before the final stones

Are placed
on the washington monument,

Another iconic structure
is already rising in new york.

At the entrance to the city
stands a mighty guardian,

The second modern wonder
of america --

The statue of liberty,

One of the most famous
monuments in the world.

Built as a gift
from France to america

To mark 100 years
of independence,

She has become an icon woven

Into the fabric
of the united states.

How do engineers create a statue
in the modern era

Worthy of the great wonders
of the world?

There are all kinds of unknowns.

There are secrets
about the statue of liberty.

There are mysteries,

And it's really a lot of fun
to try to uncover them.

Narrator:
Looking out over new york
from a staggering 265 feet,

The statue is an enduring
symbol of freedom.

Made from 62,000 pounds
of the purest copper,

Supported by an ingenious
metal skeleton...

...She stands on top of
a mysterious 11-pointed star...

And tramples on the chains
of oppression

With her enormous feet.

Holding her torch high
into the new york skyline,

She is one of the world's
most recognizable landmarks.

The statue of liberty
is a modern engineering wonder.

But what is the inspiration
for this magnificent monument?

Have the seven wonders
of the ancient world

Influenced its design?

Historian and author ed berenson

Spends years trying
to uncover the inspiration

For new york's
most famous resident.

When we try to figure out

What the inspiration
for the statue of liberty was,

We have to make
our own interpretations

Because bartholdi didn't
write down very much.

Narrator:
Completed in 1886,

The statue of liberty
is french sculptor

Frédéric bartholdi's
masterpiece.

At first glance,
it looks like the statue

Is modeled on libertas,
the roman goddess of freedom.

Berenson: Right from the
beginning, the real name

Of the statue of liberty is
liberty enlightening the world.

Narrator:
The same goddess of freedom

Also appears
on the great seal of France,

But is there more going on here?

Ed thinks bartholdi
is actually looking

Even further back in time

To one of the ancient wonders
of the world

Which experts believe features a
very similar-looking headpiece.

Berenson:
This is the colossus of rhodes,
and this was an image

From the middle
of the 19th century.

This is what people then thought
the colossus of rhodes

Must've looked like.

Narrator:
The 110-feet-tall statue

Is one of the seven
ancient wonders of the world.

It represents helios,
the greek god of the sun.

It stands on the greek island
of rhodes 2,300 years ago,

But it's destroyed just 66 years
after it is built.

It was a great statue,
a huge statue,

Carrying a torch,

With a crown
that had spokes on it,

And those spokes represent
the rays of the sun.

Narrator: So is this really
where bartholdi

Gets his inspiration from?

Berenson: We know that he was
interested in colossal statues.

He was amazed by them
and he said that he wanted

To build something
just like that.

What bartholdi did is
he amalgamated the two.

He took the goddess of liberty

And he fused it
with the colossus of rhodes,

And out of that came
the statue of liberty.

Narrator: The welcoming face
of the statue of liberty

Greets new arrivals
into new york

For more than 150 years.

But when she first rises
above the hudson river,

She looks very different --

Much more like a statue
from the ancient world.

62,000 pounds
of the purest copper

Make up the statue's skin,

Hammered into over 300 plates.

Each plate is
less than one inch thick.

A thick layer of green patina
covers every part of the statue.

But stripping away
130 years of oxidation

Reveals the lady's true color.

When first built,

She looks like a gleaming golden
colossus of ancient times,

Towering over
19th-century new york.

The statue of liberty
stands tall

As a modern wonder of america,
watching over new york city.

But the ancient colossus
of rhodes

Collapses after just 66 years.

How do engineers ensure

That lady liberty
doesn't suffer the same fate

And stands strong in the face
of ferocious atlantic winds?

And to build
another ancient wonder,

A team of engineers
in south dakota

Face an even greater
challenge --

To change the face
of an entire mountain.

Narrator: For more than a
century, the statue of liberty

Stands proudly on its plinth,
watching over new york harbor.

The famous colossus of rhodes,
on which it is modeled,

Is shorter and built
of sturdier stuff,

Yet it collapses
after just 66 years.

How do liberty's
engineers ensure

She outlives
her ancient greek ancestor?

Veteran structural engineer
donald friedman

Is one of america's
leading specialists

In renovating
historical buildings.

He investigates
how the statue of liberty

Has stood the test of time.

Friedman:
She's an amazing statue.

When you look at her
from the outside, you know,

You see what everybody
has always come here to see,

But when you go inside,
you see the structure,

And it's even more interesting.

Narrator:
Underneath her robe

Lies a vast, hidden lattice
of intricate metalwork.

A huge central pylon
anchors her to the pedestal...

...And acts as a spine
for layers of steel girders...

...Supporting a framework
of thin metal bars...

...That attach
to her copper skin.

♪

So how does this
seemingly fragile frame

Make lady liberty stronger than
the great colossus of rhodes?

To solve this mystery,
don first needs to understand

Exactly how
the colossus collapses.

Nice to see you.

Don works with veteran
physicist neville reiger,

Who has been researching
the fate

Of the massive ancient statue
for over 20 years.

This is what we think
that the colossus looked like.

It stood pretty much
with its legs close together.

Certainly not straddled
over the harbor.

In 226 b.C.,

The island of rhodes is struck
by an earthquake.

Neville has built
a computer simulation

To investigate why
the colossus falls.

It would have failed
at the ankles.

That would've brought
the entire structure down.

And that's what they saw
lying on the ground

For 700 years.

Don believes the
statue of liberty's designer

Takes this into account.

If you look at a person,
we're big in the middle

And then we get narrow
down towards the ankles,

And that's the weakest
part of a statue.

Narrator: The narrow legs
and ankles of the colossus

Make it susceptible to collapse.

So bartholdi designs liberty

To have a wide,
flowing robe at the base.

The robe makes her
more structurally sound.

The sturdy base will also

Help her deal with
a more likely threat...

Strong winds.

Friedman: The sculpture itself
is a very thin copper skin,

And even with a good shape

And even with the good geometry
that the dress gives it,

There's still the issue of how
do you make this strong enough

To withstand the wind pressure
that's blowing on it

On a day like today,
for example?

Narrator:
So why hasn't the wind ripped
off liberty's thin copper skin?

Friedman: In order to provide
the structure

For this massive sculpture,
the artist employed one

Of the most famous engineers
of the era

And arguably the best engineer
in France, at that time.

Narrator:
Bartholdi recruits

A rising star
of the construction industry,

An engineer who later builds
a tower in paris, France,

That takes his name --

Gustave eiffel.

Inside that thin copper skin,

You've got a wrought-iron
braced frame

That is the main structure
of the statue,

Designed by the engineer
gustave eiffel,

And it's very similar
to the tower

That he built in paris
a few years later.

Narrator: A solid central pylon
made from four columns

Reinforced with crossed
diagonal girders

Gives the statue super strength.

The central pylon supports
a second steel frame,

Which attaches
to the statue's skin

With flexible rods
and strips of metal.

These strips are held in place
with copper saddles

So that the two layers
move independently.

The connections between
the skin and the skeleton

Act as a spring, allowing
the statue to sway and flex.

Engineers use
cutting-edge techniques

To push the boundaries
of what's possible

To build this modern wonder.

Lady liberty may resemble the
statues of the ancient world

But stands taller and prouder

Than anything
that has come before,

An icon of american identity
in the middle of new york.

But why is one
of the most important

Modern wonders of america

Here on an island
in the hudson river?

Hidden secrets under the base of
the statue might reveal a clue.

And how do engineers
in south dakota

Carve a monumental sculpture
worthy of the ancient world

In the middle
of the american wilderness?

♪

Narrator: The statue of liberty,
a modern wonder of america

Familiar to billions
across the world.

Nearly 150 years ago,

Her designer, a french artist,
frédéric bartholdi,

Knows what he wants
his statue to look like...

But his biggest problem
is finding a place to put her.

Archaeologist joel dukes

Is on a mission to uncover
why lady liberty

Stands on an island
in new york harbor.

Dukes: Could've been
at the mouth of the harbor,

Which is several
miles up this way.

It could've been on manhattan,
at the tip,

Or even in central park.

Ultimately, though,
they decided on liberty island.

Narrator:
So why is one of the modern
wonders of america built here?

Hiding in plain sight
beneath the statue's feet

Is a military fort.

The fort is shaped like
an 11-pointed star...

And is much older
than the statue.

Thousands of precisely
carved granite blocks

Make up its walls,

And inside sits
the statue's foundations --

A massive slab
of solid concrete,

20 feet deep
and weighing 27,000 tons.

Why is the statue built
on top of a fort?

Can the unusual shape
provide a clue?

Dukes: Fort wood is a star fort,
has 11 points on it,

And the interesting thing
is that it's unique

Among the forts
in new york harbor.

Narrator: In fact, fort wood
is the only fort of its kind

In the entire united states.

And it's still giving up
its secrets.

Joel thinks he's found another
clue to the fort's violent past.

The team uncover a curved wall

That runs alongside
the existing star-shaped one.

Dukes:
Here's the island.

Here's the fort
with the 11 points

And the outer wall curved around
each of the points like this.

What we suspect
is that the wall went

Around the fort at one point.

Narrator: The more he examines
it, the more joel believes

It might be something else
altogether.

So what it looks like is
this isn't actually a wall.

What this is is a foot or two,
a support for a moat.

Narrator:
A moat here reveals soldiers
need 360-degree defenses.

They aren't just worried
about attacking ships,

But attacks from the land, too.

Protecting from a land invasion

Would've been part
of the defenses at this fort.

Narrator: The fort's unique,
11-pointed shape

Gave defenders a huge advantage.

It dramatically increases
their field of fire

And reduces blind spots.

Cannons positioned on
one side of the fort

Can fire across to the other...

[ cannons firing ]

...Hitting anyone attempting
to scale its walls.

The fort's low profile allows
for thick granite ramparts

Protecting it from cannon fire.

But the development

Of more powerful artillery
and explosive shells

Means the fort
soon becomes outdated.

And it gradually falls
into disrepair.

Dukes:
Once the fort became obsolete,

They began to repurpose it
for different things,

Such as a barracks,
and a quartermaster's

And even a lighthouse keeper's
quarter was put out there.

Narrator:
Joel believes that,

Because the fort is no longer
of military importance,

It can be repurposed easily
and cheaply,

This time as the ideal base
for a huge statue.

Dukes:
I think that it was really
fortunate to find fort wood.

I think the star design fits
really well with the pedestal

And the statue out there
on liberty island.

Narrator: Thanks to the position
of this fort,

The statue of liberty has stood
for more than 150 years

To greet any visitors
arriving into new york.

For many, this is their
first glimpse of america,

An enduring image of the promise
of an entire nation.

The statue of liberty
and the washington monument

Emulate and surpass the ancient
wonders that inspire them.

But a team of engineers
in south dakota

Take the challenge of conquering
the american landscape

To a whole new level

By constructing the most
ambitious wonder of america yet,

Mount rushmore.

And how do engineers
on the west coast

Overcome the constant threat
of killer earthquakes

To construct the longest bridge
ever attempted in the world --

A unique american wonder,
the golden gate bridge?

Narrator: The seven
modern wonders of america

Look to the ancient world
for inspiration.

Early civilizations
fill their world

With gigantic stone sculptures

That honor their gods
and rulers,

Like the great pharaoh ramesses
at abu simbel in egypt

Or the statue of zeus
at olympia in greece,

One of the original
wonders of the world.

The third modern wonder
of america

Takes this idea
to the next level

As the most ambitious
of them all -- mount rushmore.

The idea -- to honor four

Of the greatest u.S. Presidents
in history.

It's a monumental project 'cause
it hadn't been done before.

Narrator: Carved directly
into south dakota's black hills,

Four gigantic faces
tower 60 feet tall.

Hollowed-out irises
plunge 2 feet into the cliff,

Leaving a thin pillar to appear
like a sparkle in their eyes.

Epic 20-foot noses,
each taller than three people.

Intricate twisting spectacles
12 inches thick.

And finely crafted facial hair.

These incredible sculptures
take 14 years to make.

How do engineers construct

Such an epic
modern wonder of america?

It's the brainchild
of danish-american sculptor

Gutzon borglum.

Historian laura pankratz
investigates how borglum carves

His giant masterpiece
from a solid mountain.

She wants to know how he deals

With the epic
engineering challenge

He faces at mount rushmore.

Pankratz: Gutzon was
a very ambitious person.

He would say things like,

"there was great
civilizations in rome,

Incredible monuments in egypt.

I want this monument to be
around for thousands of years."

Narrator: Mount rushmore's
creator attempts a feat

Of precision engineering
not seen on this scale

In the united states before.

It was very different
to be able to remove

A small piece of stone
in the studio

In comparison to removing
450,000 tons of rock

Off of a mountain,

And one mistake,
and there's no putting it back.

Narrator: Gutzon borglum's
has to find over 400 workers

With experience
of rock-hard granite

To even begin construction.

The depression was going on,
so there wasn't a lot of work.

There was a lot
of unemployed miners here,

And they were happy
to go to work for borglum.

Narrator: Mines are dotted
right across south dakota.

Miners here
have years of experience

Removing thousands
of tons of hard rock

In search of valuable minerals,

Such as mica,
natural stone, and gold.

Borglum harnesses their
pioneering mining technology

To start transforming
a remote mountain of granite

Into a magnificent monument.

In 1927, they begin carving,

But instead of using chisels,

Workers use dynamite.

They blast away the mountain,

Leaving the outline
of four giant heads.

Next, they drill 3-inch holes
all over the rock's surface

To carve the features of
the famous faces into the rock.

And for the finishing touches,

They use air-powered hammers
to smooth the sculpture.

But how can you carve a mountain
with dynamite

While dangling
over 50 stories high?

♪

Wayne van hout runs the milbank
granite quarry in south dakota.

He's an explosives expert
and granite cutter.

Van hout: Granite is
extremely hard to work with.

A shortcut in that
is we can use explosives,

But when you use explosives,
if not done right,

It can cause damage
to the stone.

Narrator: Wayne wants
to understand how dynamite

Can help carve the figures
at mount rushmore.

He experiments
with their techniques

And starts by testing explosives
on a reject granite block.

We'll put one stick of dynashear
in each hole.

The holes here
are drilled random.

♪

Oh, that's how you
break it up good.

Of course, you don't end up
with much left when you're done.

Out here, we can do a blast
pretty much any time of the day.

At mount rushmore,
they used to do it twice a day.

The reason for that was they had
to clear the mountain

When they did do their blasting.

Everybody'd have to climb up
the ropes

And get off the mountain.

It must have been quite
an ordeal to get it done.

Narrator:
In the hands of experts,

Dynamite can remove rock

To a remarkable accuracy
of within 3 inches.

At mount rushmore,

This leaves behind
a rough outline of the face.

But how do you sculpt
the crucial final few inches?

On mount rushmore, they would
have come in with jackhammers

And start grinding that away
to make it smooth.

The polished face, they call it.

Narrator: The workers
remove the final 3 inches

With a technique
called honeycombing.

They use jackhammers to drill
a tight pattern of holes.

This weakens the granite
and allows small pieces

To be accurately removed
with hand tools.

They pound the rock
to a smooth finish

By loosening the drill bit
in their air hammers,

A method known as bumping.

I got a small 12x12 area done.

Went really fast for me,

But I'm not hanging from a rope
off the side of a mountain

Trying to go
straight in with this,

Trying to make it
all the perfect shape.

But when you're all done,

This is what they called
their polished surface.

It looks great.

Narrator: Achieving this level
of detail at the giant scale

Of mount rushmore
takes 14 years.

Borglum has to start
from scratch.

When he arrives
in the black hills wilderness,

There isn't even a road here.

To realize his epic vision,

He first needs
giant infrastructure.

A small city springs up
at the bottom of the mountain,

Complete with new roads,
blacksmith shops,

And tool sheds.

A steep, 760-step staircase

And a cable car take the workers

To the top of the mountain
over 5,000 feet high.

Winches lower the carvers
down onto the faces,

Dangling hundreds of feet
above the ground.

Giant compressors pump air
up the mountain

To power the pneumatic drills
and custom-made air hammers.

Adapting american mining
techniques allows workers

To overcome the wild
mountain range in south dakota

To forever stamp the images
of the great american leaders

On the landscape

And surpass the achievements
of the ancient world.

But is there more
to this modern american wonder

Than a tribute
to past presidents,

A hidden purpose to secure
the national identity?

Clues are concealed
inside the mountain.

And as the usa emerges
as a modern global superpower,

A brand-new record-breaking
engineering wonder appears...

...An icon of the 20th century

Unlike anything the world
has ever seen before.

Narrator:
Across the united states,

The incredible
seven modern wonders of america

Test the boundaries
of engineering.

Mount rushmore is hewn directly

Into the mountains
of south dakota

To honor the great
american presidents.

But is there more to this
monument than meets the eye?

The seven wonders of the ancient
world are riddled with secrets.

The largest of them all,
the great pyramid of giza,

Contains hidden passageways
and concealed rooms.

And mount rushmore
is no different.

Behind abraham lincoln's head
lies a secret tunnel

Extending 70 feet deep
into the rock,

But it hits a dead end.

A 1,200-pound granite capstone

Seals an underground chamber
at the tunnel's mouth.

Inside, a titanium vault

That contains
a long teak casket.

And carefully stacked inside,

16 super-thin enamel panels.

Why are these mysterious tablets
hidden inside mount rushmore,

And why is there a tunnel
that seems to lead nowhere?

In washington's
library of congress,

Architectural historian
paula reed

Hunts for an explanation.

There are thousands of documents

Detailing mount rushmore's
evolution

Among the personal papers
of its creator, gutzon borglum.

Reed:
There's a lot of correspondence,

Dealing with congress
to get funding.

A lot of the funds were matched
with private funds,

So there was also going out

And beating the bushes
for private donors,

So funding was a problem
from the beginning.

Narrator: The monument is
initially budgeted at $250,000,

But costs quickly soar
to nearly $1 million.

Reed:
They kept running out of money.

And there would be
an appropriation,

And it would get spent,
and then work would stop,

And then there would be
another appropriation.

Bair: And here we have records
that were kept in 1939 and 1940.

Narrator:
Paula wants to understand

Why the project keeps
running out of money,

So she works with
the collection's historian,

Barbara bair.

Gutzon borglum did
change his mind a good bit,

And things evolved.

Narrator: Gutzon borglum's
vision of mount rushmore

Expands over time.

They're searching for evidence

Of his most audacious
and expensive plan.

So, these are
oversize items.

Original blueprints
reveal detailed designs

For a complex around
the finished monument.

Reed: Part of the proposal
of gutzon borglum

Was to have this grand staircase
that would allow visitors

To climb all the way up
behind the heads.

Narrator:
The staircase leads

To the majestically titled
hall of records.

Borglum describes a chamber
hidden within the mountain

That explains
mount rushmore's purpose

And houses a depository of
the country's most sacred texts.

It would have copies
of important documents

Like the declaration
of independence,

The constitution,
and an explanation

Of who the heads were and why
they were on that mountain.

Borglum plans a grand hall
80 by 100 feet

Drilled behind the faces,

With an 800-foot-high granite
stairway climbing up to it.

At the chamber's grand entrance,

A bronze eagle with wings
spanning 38 feet

Sits above huge glass doors.

Inside, bronze and glass
cabinets fill the walls,

Showcasing national documents

Like the declaration
of independence.

Busts of famous americans
decorate the hall,

And the nation's contributions
to the world

Are inscribed on the walls.

Gutzon borglum wants to secure
mount rushmore's place

Among history's
greatest monuments

And america's legacy

For any future civilization
discovering it.

Borglum was so attracted
to these kind of ideas

Of colossal shrines
like the pyramids.

You see from the outside
this very monumental structure,

But if you go in the inside,
there's this secret chamber

That tell us the story
of that time period.

The records show
borglum persuades congress

To grant $50,000

For the construction
of the hall of records.

In 1938, workers start blasting
the cavity for the hall

Out of the mountain.

But world war ii forces a halt.

Congress said, "we need
this money for the war effort.

So we're done here.

Don't worry about
the hall of records.

Don't worry about
the grand staircase.

Just get the heads done."

Narrator:
The heads are swiftly completed,

And work on the monument
stops in October 1941.

Reed: The hall of records,
which had been started,

Is still left there
in its unfinished state.

Narrator:
There's still evidence

Of the moment
that construction stops.

Tool marks scar the sides
of the passageway.

In 1998,
gutzon borglum's daughter buries

16 enamel tablets
in the entrance to the chamber.

This time capsule contains
a history of the united states

And biographies of the four
presidents and gutzon borglum.

Mount rushmore was intended
to be more

Than a tourist attraction --

A high-tech repository to guard
many of the national treasures

That defined the history
and identity of the usa.

Not all of the seven
modern wonders of america

Take their inspiration
from the ancient world.

In the 20th century,
american engineers

Invent a completely new
kind of landmark...

That goes on to change
the city landscape

Unlike anything ever before.

And on the other side
of the country,

Engineers on the west coast are
building another modern wonder,

The golden gate bridge.

How can they make it
stand strong

Against nature's
deadliest killer?

Narrator: A brand-new class

Of astonishing
engineering achievements

Across the u.S.

Outsize the familiar
stone and marble wonders

Of the ancient world.

In the heart of manhattan

Stands a spectacular
icon of engineering...

...The fourth
modern wonder of america,

The empire state building.

The only way to build big
in crowded manhattan

Is to build up.

And when
the empire state building

Opens in 1931,

It's the tallest building
on the planet,

A title it holds
for more than 40 years.

Today, it's sky-piercing outline
is familiar to billions.

But the secrets to its success

Lie hidden beneath
its stone skin.

The skyscraper has a sturdy
internal structural framework.

It weighs more
than 365,000 tons.

How is such an incredible weight

Supported over
such a small area?

The empire state building is
actually a slender step pyramid

Widening towards the bottom.

This ingenious shape
spreads the weight of the tower

Across more than
80,000 square feet.

Beneath the surface,
sturdy steel columns

Firmly lock into huge foundation
shafts of solid concrete.

This base is just
three stories deep,

52 feet, a fraction
of the tower's total height.

How can such shallow foundations
support such a massive building?

Geotechnical engineer
andrew klaetsch

Thinks the secret
lies deep under new york city.

He's at a construction site

For manhattan's newest
super-tall skyscraper.

They are excavating right now
to build their foundations.

Narrator:
Andrew only has to venture
10 feet below street level

To hit the city's bedrock.

And right here is the very
surface of the bedrock today,

Right below 32nd street.

Narrator: Other skyscrapers
around the world

In london, tokyo, and chicago

Have foundations
that are twice as deep,

But new york stands
on firmer ground.

Well, what you see here
is this rock

That was once buried
at great depth

And formed under
enormous pressure.

Narrator:
This gray rock is called schist.

Klaetsch:
It reflects the light.

It actually looks like glitter,

And that is the mica minerals
in the manhattan schist.

Narrator: Manhattan schist forms
450 million years ago

When two continental
plates collide,

Pushing up vast mountain ranges.

Over millions of years,

The rocks on the surface
wear away,

Exposing incredible, strong
cores of compressed schist

That manhattan stands on today.

To find out how strong
this manhattan rock is,

Andrew takes a sample
to his lab.

He uses a compression machine
to investigate

How much pressure
it can withstand.

Much stronger.

Andrew's colleague
lysandra lincoln

Applies increasing pressure

To this 2-inch-thick
manhattan schist.

This is the load
as it increases with time.

Only up to
just over 40,000 pounds.

The sample is holding strong.

Almost 60,000 pounds.

[ boom ]
whoa.

[ laughs ]

That was pretty good,
pretty explosive.

So you can see, it shattered
into many pieces.

This manhattan schist
can withstand

A staggering 75,000 pounds
of pressure per square inch.

It can safely hold more than 100
empire state buildings.

It's exceptionally strong.

It's significantly higher
than any sort of pressure

That we'd be looking at in terms
of building foundations.

Once the construction
reaches ground level,

The entire structure is finished
in just seven months.

It's an astonishing achievement.

The ancient wonders
often take decades to build,

But the empire state building
surpasses them

In the blink of an eye.

The secret to how this
record-breaking

Modern wonder of america
is built so quickly

Lies hidden beneath its skin.

The skeleton of the entire tower

Is made from
I-shaped steel beams.

They are held together
with thousands of rivets...

...And create a massive
three-dimensional frame

Of steel boxes.

The workers simply hang
the stone facade

Onto the outside like a curtain.

They repeat the same pattern

For floor after floor
after floor.

Building nearly a story a day,

They take just 7 months
to reach 1,250 feet.

Engineer don friedman

Works with experienced
metalworker rich bauer

At a steel forge in new jersey
to explore

How the empire state building's
steel construction kit

Is pieced together
on-site so fast.

Well, right now,
we're heating up the rivet

And making sure
it gets extremely hot.

Narrator:
Rich thinks the humble rivet

Is the real hero
of the empire state building.

Bauer: Once you send it
all the way home

And make the rivet
completely up,

It's not like a nut or a bolt

That's going to loosen up
or rattle over time.

Welds could crack.

Rivets, once they cool off,
it contracts.

It makes sure that joint
is completely tight.

You want a nice,
consistent orange.

Narrator: The rivet comes out
of the furnace red-hot,

But it takes just seconds
for the metal

To become too cool to work.

Bauer:
I couldn't set this rivet now.

We'd have to throw
that rivet out

And start it over
and try another rivet.

Narrator: From the furnace
in the workshop,

It takes three people
to set a single red-hot rivet

Before it cools.

The construction of
the empire state building

Requires an astonishing level
of coordination and teamwork.

It's the first time don has seen
this process in action.

Friedman:
I've read about it, but it's
something else seeing it.

Installing rivets
requires a team of people

Working together very closely

To make sure
that everything happens

Before the rivets cool off.

Narrator: This fast cooling
poses a huge challenge

To workers at
the empire state building.

They need more than
100,000 rivets

To hold the steel
girders together.

To heat the rivets, engineers
build furnaces on each floor,

But still, the raw-steel beams
can be more than 35 feet away.

Incredibly, workers
throw the rivets.

They were trying
to throw these rivets

10, 15, 20, 30 feet
up in the air,

And they had to make sure
they do this

All before it cooled off.

Narrator: Throwing hot rivets
solves a problem,

But it's very dangerous.

It took enough skill to do this,
and you think about doing it

In the circumstances of actually
building a high-rise building,

And it's just incredible.

Narrator: The strong
and fast construction

Of the empire state building
relies on hot riveting.

The whole building goes up
like prefabricated furniture,

A 60,000-ton made-to-order
metal framework

Assembled simply on-site.

And as soon as this
basic framework is complete,

Other teams
can finish each floor.

Workers fill temporary
wooden floors with concrete

And reinforce them
with wire mesh.

As soon as the floor is set,
they lay down railway tracks

To move materials quickly from
elevators to the outer edges.

Other teams construct
makeshift cafeterias

On the uppermost floors

So builders don't waste time
going to the bottom to eat.

Finally, workers at the top
simply hang the external walls

On the steel skeleton.

The building soars
at a lightning-quick pace.

Innovative building techniques

And clever time-saving solutions
like these

Mean the empire state building
takes less than 14 months

To build, completing in 1931.

Far faster than the decades

Many of the ancient wonders
take to build.

President hoover
turns the lights on

From the white house in
a spectacular opening ceremony.

The empire state building
stands to this day

As an american icon...

...The familiar outline
of its incredible spire

Recognizable to billions
around the globe.

But why is the building
this shape?

What engineering secrets
are hidden inside the spire

Of this modern wonder
of america?

And at the same time,
on america's pacific coast,

The longest ocean crossing
ever attempted is under way --

The golden gate bridge.

How do engineers protect it
from killer earthquakes?

Narrator:
The empire state building

Is the first of the seven
modern wonders of america

To top 100 stories...

Far surpassing
any of its ancient predecessors.

But what does
the empire state building's

Record-breaking height reveal
about its forgotten history?

Friedman:
We're in herald square,
which is one of the busiest

And most crowded parts
of the city,

And there's
the empire state building

In front of us at fifth avenue.

Narrator: Don friedman believes
the empire state building's

Distinctive spire sets it apart
in the city's crowded skyline.

With that, you go, "oh.
That's the empire state."

Narrator: But this mast
also hides a secret.

In 1929, the architects
set out to construct

A very different building.

Friedman:
This is an early drawing.

There's one thing missing here,
which is the spire,

Because this drawing was created

Before the spire
was added to the building.

Narrator: The blueprints reveal
that empire state building's

Elaborate spire
is a very late addition.

Engineers shoehorned it
into the design

Only after construction starts.

Why add extra height

To an already
record-breaking wonder?

♪

In 1930, the steel-and-glass
spire starts to take shape.

At the top, on floor 102,

An observation deck
offers breathtaking views.

One floor above
is a strange balcony,

With a knee-high wall
as the only barrier

To a 1,250-foot drop.

Incredibly,
the architects declare

This is for giant airships
to dock

And unload passengers directly
into the empire state building.

But is this the real reason
for the spire?

In the early 1930s, docking
an airship with a skyscraper

Is a radical new idea.

Airships don't need runways.

They simply attach to towers
or masts using ropes.

Forward-thinking building
designers place mooring points

On the top of their structure,

Looking forward to a future
of airship-filled skies.

In 1931, airships try to dock

At the empire state building's
spire.

It's such a jaw-dropping sight,
crowds block the sidewalks

And the busy streets below.

One airship clings on
for 3 minutes.

Another drops a bundle
of newspapers.

No passengers disembark,

And the attempt
is never repeated.

Why is this airship
the only one to dock

At the empire state building?

Civil engineer
maarten van reeuwijk

Thinks he knows the answer.

He's investigating
the empire state building's

Forgotten airship port.

He re-creates the conditions
faced by the docking airship

In this wind tunnel
at imperial college london.

Maarten wants to find out if an
airship could offload passengers

At the top of the world's
tallest building.

What I have here is a balloon,
which is filled with helium,

And this is going to be
a very rough approximation

To the airship,
and what I'm going to do is,

I'm going to moor this airship

On the top of the building
right here.

Narrator:
The tunnel's fans start up.

Maarten adds smoke to see
the path of the wind.

So here, you can see the flow
as it goes around this airship.

Narrator: The wind that hits
the top of the building

Must go somewhere.

It deflects to
the building's sides,

But it also goes up.

You see that this highly
unsteady flow in the wake

Causes huge response
from our airship.

Narrator: The airship
and all its furniture, luggage,

And passengers would be
hurled around inside.

Van reeuwijk: We're seeing very
violent motions of the airship.

Full-scale, these would be
ups and downs of the airship

Of 10, 20 meters.

This would be hugely dangerous.

It's not the greatest of ideas
to try to moor an airship

On a building like
the empire state building.

Narrator: Tall structures
like skyscrapers

Can create strong updrafts of
wind and unpredictable gusts.

Airships need a second tether
to hold their tails in place

And stop them from tipping up
in these updrafts.

The tail tether should rotate

And allow the airship to align
with gusting winds.

But the empire state building
doesn't have this mechanism.

Any airship can only moor
for a few minutes

Or drop a bundle of newspapers
before moving on.

Tethered precariously just
to the mast of the skyscraper,

This is all they can
safely achieve.

In 1931, the world's
top airship captain,

Germany's hugo eckener,
visits new york.

He concludes that any attempt
to drop off passengers

At the empire state building
would end in disaster.

A few years later, the explosion
of the nazi airship hindenburg

Underlines the dangers.

Man: The world's largest
and most luxurious airship,

The hindenburg,

Burns in a disaster.
[ crowd screaming ]

This tragedy dramatically ends
a future era of airship travel.

Narrator: Don believes
the real reason for the mast

On the empire state building

Lies with an intense rivalry
that grips the city.

People were building taller

And taller buildings
in new york.

Chrysler building was the
tallest building in the world

For about a year.

By adding the spire onto
the empire state building,

It went up about
another 15 stories in height.

Narrator: The spire allows
the empire state building

To soar above its rivals,

And it protects its record
far into the future.

Friedman:
Any publicity will help,

And constructing the tallest
building in the world

Is one way to get
a lot of free publicity.

Narrator: When complete,
the empire state building

Is the tallest structure
on planet earth.

Towering over every
ancient wonder of the world,

It stands as an icon
of american engineering,

Ingenuity, and ambition.

Incredibly, at the same time

The empire state building
breaks world records,

Engineers on the other side
of the country

Are constructing the longest
bridge ever attempted --

The golden gate bridge.

But they're constantly
under attack

From the very ground
they build on.

How can engineers ensure
the record-breaking bridge

Can stand firm on the most
unstable ground in america?

And below in the bay,
another team of engineers

Are busy constructing the most
notorious wonder of america --

Alcatraz.

How has "the rock" maintained
its unbreakable reputation

Against san francisco's
killer earthquakes?

Narrator: The seven modern
wonders of america

Herald a brand-new class

Of astonishing
engineering achievement...

To surpass the old wonders
of the ancient world.

They stand prouder...

Rise taller, and completely
transform the landscape.

The fifth modern wonder
is on america's west coast,

Here in san francisco...

The golden gate bridge.

The golden gate strait
is a mile-wide channel

Between san francisco bay
and the pacific ocean.

In the 1920s, the only way
to cross the strait is by ferry.

And by 1929, there are
2 1/2 million car trips a year

Across the bay.

The city tasks joseph strauss,
an accomplished architect,

To design a bridge
to cross san francisco bay

And link it
to the city of oakland

On the other side.

But spanning the fast-moving
and treacherous waters

Is an incredible challenge

That requires a structure
dubbed "the impossible bridge."

To achieve his task,
strauss must construct

The most ambitious bridge
the world has ever seen --

A two-tower suspension bridge
of epic proportions,

The six-lane superhighway

Stretching for more
than 1.7 miles,

With the longest span
ever attempted,

A masterpiece
of bridge engineering.

Work begins in January 1933.

Two colossal towers
each weigh 22,000 tons

And stand 746 feet
above the water.

They will carry the entire
weight of the bridge.

But there's a problem.

The towers sit on
a tectonic time bomb.

San francisco experiences
killer earthquakes.

Only 30 years before, in 1906,

A massive quake measuring 7.9
on the richter scale

Rips through the city.

Hundreds of buildings collapse,

And over 3,000 people
are killed.

More than 80% of the city
is destroyed.

The 1906 earthquake is
one of the worst and deadliest

In the history
of the united states.

San francisco is under
constant attack from the earth,

Usually recording
20 tremors a day.

The city sits directly above two
colliding continental plates,

Which means another devastating
earthquake is inevitable.

Engineers have to make sure
the golden gate bridge

Can stand up to the big one.

They sink waterproof walls
into the ocean,

Pump out the water, and dig
holes deep into the seafloor.

Then they pour in 150,000 tons
of concrete

To build mighty foundations
rising from the rocks below.

They assemble two
746-foot steel towers on top

And link them with
80,000 miles of steel wire.

Finally, they sink concrete
blocks deep into the banks

To anchor the cables

That hold up the most iconic
suspension bridge in the world.

In 1989, the city of
san francisco is tested again.

A magnitude 6.9 earthquake
shakes the city to its core.

Among the damage, the oakland
bay bridge partially collapses.

One motorist loses their life.

♪

But the golden gate bridge
survives intact.

Earthquakes are terrifying

Because they can strike
without warning.

But the golden gate bridge
stands tall and confident

Against anything nature
can throw at it.

Building the impossible bridge
is one of the greatest

Engineering achievements
of the 20th century.

It pushes the boundaries
of bridge design

And demonstrates to the world

That the usa can overcome any
problem that nature can throw.

This modern wonder of america

Spans some of the most
treacherous waters

In the country --

Icy cold, 100 yards deep,
and full of vicious currents.

These same waters are home

To the most notorious
wonder of america --

Alcatraz.

But why do engineers build

The world's first supermax
penitentiary in san francisco,

The country's
earthquake capital?

Narrator:
In only two centuries,

The united states constructs
the most extraordinary monuments

To match
the engineering achievements

Of the entire ancient world.

Across the continent,

Engineers must overcome
the challenges of building

In a wild and untamed landscape.

The sixth modern wonder
stands alone,

Surrounded by
treacherous icy water

In a deadly
earthquake hotspot...

Alcatraz...

A name feared around the world.

♪

Alcatraz stands more than a mile

Out into the waters
of san francisco bay,

Its iconic prison block a beacon
of crime and punishment.

For decades, this island is home

To the most wanted men
in america --

Al capone, machine gun kelly,

Robert stroud, "the birdman."

The convicts that come here
cannot be held anywhere else.

What engineering secrets

Lie behind
its legendary reputation?

The rock is designed as a prison
inside a prison.

The outer wall
is over 2 feet thick.

Inside are over 300 cells
stacked three stories high.

And a 2-ton steel door
blocks the only exit.

Outside, 12-foot-tall fences
topped with razor wire,

All surrounded
by six tall watchtowers

With guards who shoot to kill.

Alcatraz is the original
supermax penitentiary,

But why is the world's
first maximum-security prison

Built here?

Most of san francisco
stands on land

Reclaimed from the ocean.

The bay mud
allows the city to grow,

But this soil is wet and soft.

The 1906 quake turns the ground
into quicksand.

More than 28,000 buildings
are destroyed,

Including four
of the city's prisons.

Lines of evacuated convicts
walk the streets,

But the citadel in alcatraz sits
directly on hard rock.

The shock waves pass through it,

And it survives the quake
with barely a scratch.

Alcatraz is the last functioning
prison in san francisco,

So the city ships its prisoners
to the rock.

The island's bedrock
lays the foundations

For its unbreakable reputation.

Soon after the quake, the iconic
prison we see today is built.

In 1934, the island becomes
a federal penitentiary,

Home to convicts
no other prison can hold.

The authorities are confident

That prisoners are locked up
solid on the rock.

But that doesn't stop many
from trying to escape.

Any prisoner wanting
to break the rock

Has to first deal with solid
iron bars in every cell...

Thick concrete walls,

And watchtowers
where guards shoot to kill.

But it is the landscape
and geology of the rock

That pose the greatest threat
to any prisoners on the run.

In 1962, the most notorious
escape from alcatraz

Ends in mystery.

Three escaping convicts --

Frank morris and brothers
john and clarence anglin --

Stand at the water's edge.

They have an improvised raft
made from raincoats.

Freedom is within reach,

But these are
treacherous waters.

Draining away the bay
reveals hidden dangers.

Across the rocky seafloor

Are caverns and peaks
the height of houses

That churn the tides into fast,
unpredictable currents

Around alcatraz.

Averaging just 17 feet deep,

The tides sweep the water
out towards the bridge,

Where a perilous ravine
plummets 360 feet.

It forces 20 times more water
through the narrow channel

Than cascades
over niagara falls.

Do the inmates
overcome these deadly currents,

Or do they get washed out
into the open ocean?

Physician dr. Tom nuckton
is an authority

On swimming in the bay.

He knows just how dangerous
these waters are.

Tom uses this huge scale model,

Built by the u.S. Corps
of army engineers,

To chart the men's escape route.

This simulator, just outside
the city in sausalito,

Replicates the current
in the entire san francisco bay.

Nuckton:
This model is really impressive.

You can see alcatraz here,
the shallow areas.

Narrator: Tom investigates
the tides around alcatraz island

At the time of the escape.

Nuckton:
So we can put this boat...

In the water

Right about where we think
the prisoners got in the water,

And we can squirt a little dye.

Okay, we have a boat
that represents

The raft of the prisoners

And some dye that shows
the outgoing tide

That the prisoners would have
had to contend with.

Narrator:
The currents push the boat

Towards the golden gate bridge.

Nuckton: They'd be swept right
out into the pacific ocean,

And you can still see the dye.

Look how quickly it's moving.

Narrator: The model shows
the most likely scenario --

The currents sweep the little
raft straight out to sea.

Frank morris and the anglin
brothers are never found.

The official report concludes

That the men drown
after their raft fails.

The rock retains
its perfect reputation.

In 1963, alcatraz
is consigned to history,

As it closes its doors forever.

But engineers continue to push
the boundaries of construction,

And only three years later,

Work begins on the seventh
modern wonder of america.

This would be the greatest
of them all,

Towering higher
than any man-made structure

The world has ever known...

...Rising in downtown
new york city, the twin towers.

Narrator: The final
modern wonder of america

Is remembered across the globe
for its tragic final moments...

...The world trade center
twin towers.

The story of their origins
is rarely told.

The world trade center
twin towers

Are america's
most iconic buildings

And her greatest
engineering triumph,

But the largest modern wonder
of america

Faces huge challenges
before construction begins

That test engineers
to their limits.

Hidden below the pavement,
engineers

Encounter water-logged mud
and rubble,

Including a 400-year-old ship
preserved in mud.

As they dig deeper,
a modern obstacle emerges --

An active railway tunnel

That carries
100,000 passengers per day.

Even further down,
70 feet below street level,

They finally reach bedrock.

This exceptionally hard material
is the perfect base to build on,

But here on the southern tip
of manhattan,

There's more than 70 feet
of soft ground

Between the surface
and a suitable foundation.

Structural engineer rick ellman
investigates how it is possible

To build a skyscraper
on reclaimed land.

Ellman: These tall towers
that are all around us,

If they were not
constructed properly,

They would lean
and very likely topple over.

Narrator:
The most famous example of the
dangers of unsteady foundations

Is the tower of pisa in Italy.

It is built on marshy land,

Similar to the reclaimed land
of manhattan.

Over time, the soft ground
causes the tower

To tilt dangerously.

But unlike pisa, manhattan has
an incredibly tough bedrock

Below the reclaimed land,
manhattan schist.

The twin towers' foundations
can be firmly anchored

Into this solid rock,
but there's a huge problem --

Reaching it.

Ellman:
Excavating in reclaimed land
can be a real challenge.

Because of the weak soils
and the high ground water,

You're unable
to just simply excavate.

Narrator:
If they excavate, water and mud
just slide back into the hole,

So engineers come up
with an ingenious solution --

They create a surrounding wall
around the foundations.

The wall acts
as a protective barrier.

First, they dig long trenches
around the edge of the site

And fill them with
a liquid slurry

To stop them collapsing inwards.

Then they drop reinforced
steel cages into the trenches

And pump in concrete
to displace the slurry.

Once these concrete walls
set solid,

Engineers can excavate
everything inside them,

Creating a giant
underground bathtub.

Instead of holding water in,
the bathtub keeps it out

So the foundations
can now be built.

They need to create room
for 50,000 people

In only 16 acres of land.

So they have to build tall.

Engineers need to push
the boundaries

Of what is possible
to raise these giants

Higher than any structure
the world has ever known

And ultimately create
a modern wonder of america

That would be copied
across the globe.

What are the engineering secrets

That allow the
world trade center twin towers

To soar higher
than anyone thought possible?

Narrator: The world trade center
twin towers

Is one of the modern wonders
of america.

The towers' tragic final moments
shake the world to its core.

But their structural genius
is often overlooked.

They are america's greatest
engineering achievement.

How do engineers push the limits
of high-rise design

To build taller
than anyone in history?

And why do they become
the blueprint

For thousands of skyscrapers
that follow?

Japanese-american architect
minoru yamasaki

And american engineer
leslie robertson

Devise a revolutionary plan
to maximize floor space.

Instead of spreading the load
across a grid,

Yamasaki creates a super-strong
hollow structure.

All the weight is supported
around the edge.

It's a breakthrough
in skyscraper design.

Each tower is made up
of 236 steel columns.

They stand just 26 inches apart
around the perimeter.

More than 43,000 windows
complete the outer skin.

Inside, steel plates stretch
across the void,

Topped with nearly
a million tons of concrete

To create 110 floors.

The north tower is crowned
with a final feature --

A 360-foot communications mast.

Now they have a new task --
to make this outer skin

Strong enough to support
the weight of the tower.

♪

Professor adrian bruegger
wants to understand

How the twin towers break
the mold of skyscraper design.

Adrian has rare access

To the surviving structures
of the twin towers,

Carefully conserved
in the basement

Of the 9/11 memorial museum.

He examines
the surviving columns

From the outer skin
of the building.

So here you can see one of those
mega columns

That is landing the forces

From 110 stories
into the ground.

And if we look up at the column,
we'll see that one of these

Large columns goes through this
beautiful trident structure,

Then picks up
three smaller columns.

Narrator:
The hollow building structure is
a breakthrough in engineering,

But this revolutionary concept
goes even further,

To the skeleton itself.

This column is actually hollow
on the inside,

And that's purposely done

So that we can
increase its stiffness.

So the material is all
along the perimeter.

Narrator:
Not only is the building hollow,
but the columns are hollow, too.

Finally the designers use
an extra trick

To reduce the overall weight
of the twin towers.

The metal is 4 inches thick
at the base

But tapers to just 1/4 of
an inch at the highest point.

Bruegger:
They get lighter and lighter
as you go up to the top.

And that is essentially
to make the building

As efficient
as humanly possible.

So this is how
structural engineers

Are able to build this high.

Narrator: Structurally
the design is perfect.

It breaks through
the constraints

Of contemporary
skyscraper building.

With this method, the height
seems almost limitless.

The twin towers,
revolutionary skyscrapers

That have changed
the world forever.

What can we learn
from the towers

And the events
that lead to their collapse?

The impact of two
hijacked airplanes

Creates massive gashes
in the towers

And an unprecedented fire
that causes them to collapse.

2,753 people die,

But the buildings put up
a remarkable fight

In the face of the attack.

On the north face
of the north tower

2/3 of the columns
were taken out,

But yet the towers stood
for more than an hour,

Which allowed occupants

Who were below
the floors of impact to escape.

Darton:
The death toll was horrific,

But had they not been
as well-built or engineered

In the wonderful way
that they were,

They probably would have
collapsed much earlier

And the death toll would
have been exponentially higher.

Narrator: Today at ground level,
massive voids

Show the footprints
of the towers.

♪

So this is the north tower
memorial pool,

And the memorial pools mark
the location

Of where the towers stood
at the street level of the site.

And here, etched in
the bronze parapets,

Are the names
of the nearly 3,000 people,

Including my brother,
who perished on 9/11.

Narrator: The world
trade center's twin towers

And those who lost their lives
in 9/11

Are never to be forgotten.

♪

The towers rose
on new york's skyline

As a powerful message
of american innovation,

Breaking boundaries
and reaching higher

Than anyone
had ever gone before.

13 years after the 9/11 tragedy,

A new building opens
at the world trade center site,

The one world trade center.

Rising 1,776 feet to commemorate
the founding of the nation,

It is new york's
new tallest skyscraper.

♪

In just two centuries,
the united states of america

Has matched the size, scope,
and ambition

Of the original seven wonders
of the ancient world...

...And has set new standards

For the ultimate achievements
of humanity.

Building taller, longer,
and higher,

The american people have tamed
the wild geography

Of this extraordinary
new continent

To build seven modern wonders

That help to define the identity
of the united states of america.

-- Captions by vitac --
www.Vitac.Com

Captions paid for by
discovery communications

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