All language subtitles for Life.After.People.S03E07.1080p.WEB.h264-EDITH_track3_[eng]

[tense music]
[birds chirping]

- [Narrator] What would happen

if every human being
on Earth disappeared?

No matter how we might vanish,

[tiger growls]

this is the story
of what could happen

to the haunting world
we leave behind,

now on "Life After People."

[static crackles]

Some of mankind's greatest
feats of engineering

were built to be indestructible,

but without us, will they
stand the test of time?

[building crashing]

Or will the elements
find a fatal flaw?

New York City's
invincible Freedom Tower

outlasts the city
it was built in,

but nature doesn't give up.

- It's designed to withstand
things like weather

and natural disasters,
even attack.

The question is: will it?

- [Narrator] An
impenetrable stronghold

guards all of humanity's
greatest treasures

while the elements
try to break in.

- The door to the vault
alone weighs 20 tons,

so that's the equivalent
of three or four elephants.

- [Narrator] And the Torre Mayor

faces off against the
earthquake capital of Mexico.

[rubble crashing]

- Built in the Ring of Fire,

this tower was designed to
take all kinds of abuse.

- [Narrator] Humanity's
unbreakable fortresses

go toe-to-toe with the fury
of a world without people

to find out what falls

and what will be the
last structure standing.

Welcome to Earth,
population: zero.

[tense music]

50 years after people,

the world is unrecognizable.

In Sydney, Australia,
the famous Opera House

is crumbling into the Pacific.

In New York City, the
Flatiron Building is in ruins.

Grand Central Station's roof
has long since collapsed.

But among the ruins, one
iconic landmark still stands,

a symbol of America's
freedom and strength.

It was built to be
nearly indestructible:

One World Trade Center.

[dramatic music]

- After 9/11, whatever was
going to take the place

of the World Trade Center
had to be significant.

It couldn't just be a feat of
architecture or engineering.

It had to be something
that would restore faith,

rebuild confidence in
the American spirit.

- When it was built,

the designer specifically
chose a height of 1,776 feet

to honor the year
that the United States

declared independence.

- The perimeter is framed
with about 45,000 tons

of high-strength
structural steel.

It's fitted with
13,000 glass panels,

each of which weighs
about 6,000 pounds.

- [Narrator] For 50 years, the
Freedom Tower has stood tall

while buildings
all over the city

have succumbed to the elements,

thanks to a near-unbreakable
concrete core

rising from her foundations
to her uppermost floors.

- The core is four feet thick

and reinforced with
steel barriers,

so you can think of that
as the building's spine

that's holding
everything together.

But the concrete
is no ordinary mix.

It's rated at 14,000 PSI.

That is strong enough that
just one square inch of it

could handle the
weight of four cars

stacked on top of one another.

- It's the most fortified
part of the whole structure.

It's a powerhouse of
design, built to last,

even when everything around
it is falling apart.

[building crashing]

- [Narrator] For decades,

One World Trade has weathered
storms, floods, lightning,

and wind, a towering beacon
of strength and engineering.

But all around her, other
towers aren't as lucky.

- Surrounding buildings like
200 Vesey and 225 Liberty

were built in the 1980s,

but neither tower is nearly as
robust as the Freedom Tower.

- [Narrator] In
the time of people,

the buildings' steel skeletons
and concrete foundations

received regular
inspection and repair.

But after half a century
without maintenance,

200 Vesey shudders,

[building crashing]

and chunks of her
facade give way.

- The building is less
than half the height

of the Freedom Tower, but
chunks of concrete and glass

would crash into the lower
third of the building

and slam into its base.

[building crashing]

- The Freedom Tower's core was
built to withstand a pressure

of 14,000 pounds
per square inch,

but a 10-foot chunk of
concrete falling 300 feet

could generate double that,

depending on how it
falls and how it lands.

- [Narrator] The
damage isn't fatal,

but it leaves the
tower vulnerable,

and an ancient enemy has been
lurking beneath the tower

all along, waiting to
exploit any weakness.

- Turns out, this
part of the city

was never meant to exist
in the first place.

Centuries ago, Lower Manhattan
was all wetlands and water.

- When construction teams
dug out the foundations

for the original One
World Trade Center,

they actually found the timbers
of an 18th-century boat,

because this area was
used to dock boats

on the Hudson River.

- Engineers came up with a
pretty brilliant solution:

a massive underground wall.

They dug 90-foot trenches

and filled them with
a special slurry

made of bentonite clay.

- Concrete was then pumped
in, forcing the slurry out,

leaving behind concrete
walls that provided a barrier

between the buildings
and the seawater.

- [Narrator] The wall
wrapped around the entire

16-acre site, a sunken
ring of concrete

holding back the Hudson
like an underground dam.

For over a century,

this massive concrete
barrier held the line.

Without people, the engineering
that once defied nature

is showing its age.

Each falling building
has been an assault,

and it's riddled with
cracks and fissures.

Finally, the wall gives way.

[water crashing]

- The river surges in,

filling the lower levels
of One World Trade Center

with 50 feet of water.

[tense music]

- Now, typically, operators
would man the pumping systems

to keep the building safe,

but 50 years after people,
those systems are long dead.

- The water has nowhere to go,
and so the salt starts to

corrode the steel
reinforcements.

- [Narrator] Lower
Manhattan has returned

to its watery roots,

its foundations drowned,
its streets mostly sunk.

As moisture seeps
into the cracks

in the Freedom Tower's core,
how much longer can she stand?

Across the Atlantic, behind
concrete walls and iron gates,

lies a citadel of secrets,
a fortress built to guard

mankind's greatest treasures:
the Geneva Freeport.

Priceless art and treasures
aren't displayed;

they're entombed,
stored in vaults

people were never meant to see,

preserved for a future
that will never come.

- A free port is basically
a designated economic zone

established in a given country

where the normal
rules don't apply.

The duties and taxes are low
or maybe even nonexistent.

Import and export
laws are different.

So this one might be in Geneva,

but it's basically like
its own tiny country

that's in the
middle of the city.

- Very few people are
allowed in or out.

Records are hard to find.

The whole idea of the place

is that the outside doesn't
know what's going on inside.

It sounds like a
James Bond movie,

but this is actually real.

- Experts believe it holds
about 1.2 million pieces of art,

but masterworks by artists like
Picasso, da Vinci, Andy Warhol,

nearly $100 billion
worth of art.

- [Narrator] Here, the relics
of humanity are sealed away

by systems purpose-built
to outlast anything,

including the end of mankind.

- These aren't just rooms,

they're vaults designed to
withstand really anything

nature can throw at them.

Inside, the temperature
is a crisp 69 degrees

with about 55% humidity.

These are perfect conditions
for maintaining masterpieces.

- [Narrator] Long after
mankind disappeared,

the free port still does the
work it was meant to do.

- The building was designed
with thick, concrete walls

and no windows, so even
though climate controls

have been dead for years,
the treasures inside

aren't subject to the heating

and cooling cycles
happening on the outside.

- There will be some
fluctuations in temperature,

but nothing like what would
be happening in museums

and private collections.

Those places were
made to display art.

The free port is designed
to protect it at any cost.

- [Narrator] Beneath the
free port's concrete skin,

a critical defense is
starting to give way.

For decades, it held the line,

keeping secret treasure
sealed and safe.

But now, its time
is running out.

- There's a protective
rubber membrane

on the roof of the free port
that's actually flexible enough

to expand in the summer heat

but contract in the winter
cold without cracking.

- The life expectancy
of this kind of roof

is 30 to 40 years.

There's an outside chance it
could last up to 50 years,

but that's the maximum it
could possibly hold out.

- [Narrator] 50
years after people,

the protective
membrane is failing,

and the roof is expanding
and cracking in the heat.

For the first time, the
free port's defenses

have been breached,

and the question isn't if
something will be destroyed;

it's what goes first.

- Free port was designed
to be airtight, watertight,

and nearly impervious.

Now, even a small crack or
leak can change everything.

Moisture and humidity seep in.

Mold colonies explode.

Nothing would be
safe from decay.

- [Narrator] In just 24
hours, mold begins to grow.

Soon, spores and fungus

crawl through the
free port unchecked.

But there's another intruder
as well, one faster, hungrier,

and drawn straight to what's
most valuable: silverfish.

- Silverfish aren't fish, and
they aren't made of silver.

They're tiny, wingless insects

notorious for sneaking
into buildings

through any available crack.

- Silverfish have a unique
ability to digest cellulose,

that's the starchy
part of a cell wall.

So they eat things
that other bugs don't.

Things like canvas,
or paper, or glue.

- That unique digestive ability

means bad news for any
collection of manuscripts,

or paper money, or paintings,

'cause those all would be
delicious meals for silverfish.

- [Narrator] The most
expensive painting ever sold,

a 500-year-old masterpiece
by Leonardo da Vinci,

is now under siege, as
countless tiny mouths

tear into the canvas,
erasing it from history.

The vault, built
to be impregnable,

has become anything but.

Now that its defenses
have been breached,

how long can its
treasures survive?

[tense music]

- [Narrator] Five
decades after people,

once one of the most densely
populated cities in the world,

Mexico City, is now a wasteland.

Chapultepec Castle,

once the only royal
palace in North America,

now lies in ruins.

Only the twisted husk of
Mexico's largest arena,

Banorte Stadium, remains,

its walls and stands
long since shaken apart

by an endless string
of earthquakes.

- Each year, Mexico City
and the surrounding area

are hit by as many
as 100 earthquakes

measuring at least four
on the Richter scale.

That magnitude means you can
feel the quake 60 miles away,

and it can do at
least some damage.

- [Narrator] Amid the
wreckage of the fallen city,

one structure refuses to fall.

It was designed to
survive in one of the most

seismically active
places on Earth:

the Torre Mayor.

- It's 738 feet tall,

about four times the
height of Niagara Falls.

It's pretty rare, though,
to have buildings this size

in this part of Mexico because
of all the seismic activity.

[tense music]

Unfortunately for Mexico City,

it was initially built on top
of a lakebed of soft clay.

Here's the problem:
unlike solid rock,

where the shockwaves would just

cause a bit of
shaking and dissipate,

this mushy earth traps
and amplifies them.

So it can make a slight rumble

turn into a serious shakedown.

[building crashing]

- [Narrator] The tower
was designed to withstand

an 8.5 magnitude earthquake,

even though the
ground beneath it

shouldn't be able to
support its weight.

- The Torre Mayor was built on
reinforced concrete caissons

driven more than half a
football field into the ground.

- Its architects knew
that if the Torre Mayor

was going to last, they needed
to pull out all the stops,

and so they used what's
known as viscous dampers.

- A viscous damper is
essentially a shock absorber,

but a really big one, and
it's filled with a fluid.

- 98 of these are spread
throughout the frame

of the Torre Mayor.

- These viscous
dampers don't actually

stop the shaking completely,
it just slows it down

so that the building
can easily handle it.

- Back in 2017, a 7.1 magnitude
earthquake struck Mexico.

[tense music]

Nearly 200,000 buildings
were destroyed in that quake,

but Torre Mayor was
not one of them.

- [Narrator] The ground rumbles,

and an earthquake turns
the Museo Soumaya,

once the most visited museum
in the entire country,

into rubble.

The Torre Mayor brushes
away the danger,

but another threat is rising.

Popocatepetl, a towering
volcano just 43 miles away,

growls beneath its
ice-capped peak.

What will happen to one of
Earth's strongest structures

when the sleeping beast erupts?

[volcano rumbles]

[tense music]

In Switzerland, 75
years after people,

the free port that was meant
to be an impenetrable vault

has cracked open.

Rot and insects have snuck
in through the cracks,

wreaking havoc on the sections

they've managed to
worm their way into.

- Those million pieces of art,
Picassos, Warhols, da Vincis.

Some of humanity's
greatest masterpieces

are now just decomposing.

- Ancient artifacts
once perfectly preserved

are now covered
in dirt and dust.

- [Narrator] Deep
within the free port,

even 75 years after people,

some of the remarkable
fortress's rooms

are still sealed,

but the climate controls
that once kept them cool

have long since failed,

and some precious artifacts
hide an incendiary secret.

- Tucked away in
one of these vaults

are priceless film archives.

But there's a problem.

These early films were made
from cellulose nitrate,

essentially gun cotton that
was turned into film stock.

- Geneva may not
be known for heat,

but summer temperatures
here can hit the 90s.

And now, with the ventilation
systems long dead,

heat seeps in through
the cracked roof

and stays trapped inside, slowly
roasting everything within.

- The free port's
thick concrete walls,

originally designed to keep
the temperature stable inside,

are now working against it,

trapping the heat, turning
it into a giant oven.

- And here's the scary part.

As nitrate film ages,
it releases gases:

nitric oxide and
nitrogen dioxide.

If these gases build up inside
of a sealed film canister,

it can cause them to explode

if the temperature hits
around 100 degrees.

Guess what?

It's already way hotter
than that inside.

- [Narrator] With a crackle
no one's left to hear,

one wheel erupts in flame.

[fire roars]
Then another, and another.

- The free port has an advanced
fire suppression system

that essentially sucks
the oxygen out of the room

and replaces it with other
gases, suffocating the fire.

It's designed to put
out fires without water

or chemicals that could
damage priceless artifacts.

- The fire suppression
system itself

doesn't require electricity,

so that would work perfectly
even decades after people.

But the problem is, the
systems that detect a fire

are electrical.

So all those extinguishers

would be sitting
there, ready to go,

not knowing that they're
supposed to be turned on.

- [Narrator] All it would
take is a small current,

the twist of a knob.

But 75 years after people,

there's no one watching,
no one to sound the alarm.

- Once the nitrate film catches
fire, it's like a firestorm.

It gets over 4,000
degrees Fahrenheit.

For reference, steel
melts at 3,000.

Concrete starts to
break down at 600.

So, 4,000 degrees, the whole
vault is in huge trouble.

[intense music]
[fire crackles]

- [Narrator] The
building was designed

to protect mankind's
treasures forever.

But this fortified vault is
under assault from the outside

and from within.

How long until what was once
unbreakable is finally broken?

In New York City,

switchgrass rustles where
tourists once swarmed.

Turtles bask on the steps of
the New York Stock Exchange.

And in Times Square,

wild pigs root through
moss and shattered neon.

- Now, there's no
native population

of feral hogs in
New York City today,

but they are widespread across

several parts of
the United States.

They're very adaptable, and
they can basically eat their way

into any place they want to go.

They're excellent colonizers.

These pigs would have
decades to migrate.

They've got no people
to keep them in check,

so they're gonna spread
very easily from the South

and from the Midwest
all across the country.

And they could very
easily travel the bridges

and tunnels from New
Jersey to Manhattan,

just like commuters do today.

- [Narrator] The skyline
is completely transformed,

tall towers all but disappeared,

but the Freedom
Tower still stands,

even as the saltwater
submerging Lower Manhattan

has reclaimed
everything around her.

- It's almost unthinkable
that it's still upright.

That base has been
wading in brackish,

salty water for years.

It's really a testament
to what we built.

- [Narrator] The tower is
unbroken, but not unscarred.

And 75 years after people,

the weight of her own spire
is becoming too much to bear.

- One of its most iconic
features is the spire,

a 408-foot-tall steel structure

that once served as
a broadcast antenna.

- The spire was made up of
18 different pieces of steel,

each of which was so heavy

that many of them
couldn't travel by road.

They had to come on a
one-month voyage by barge

down to New York
City from Quebec.

- The steel was hot-dipped
galvanized in molten zinc

to keep rust at bay
for up to 75 years.

But now, that protective
layer has given out.

After 12 decades
without maintenance,

corrosion has set in.

- [Narrator] With a gust
of wind, the spire buckles,

and One World Trade Center's
own body now turns against her.

- That spire doesn't just fall,

it punches through the tower
like a steel battering ram.

Floors 90 to 60,
gone in seconds.

It's like watching a sword

slice through a
stack of pancakes.

Only the pancakes are 30
floors of crumbling concrete

and rusted steel.

- [Narrator] Concrete splinters.

Steel snaps like bones.

The powerful core
that sustains her

is now fractured and weak.

How much longer can the building
designed to stand forever

actually last?

[tense music]

- [Narrator] A
century after people,

earthquakes have turned most
of Mexico City into rubble.

[birds chirping]

Hawks and ospreys now nest
where sightseers once strolled,

and bobcats hunt mice
and red-bellied squirrels

in the remains of
the oldest cathedral

in all of Latin America.

Through it all, the nearly
invincible Torre Mayor

has held fast.

But now, there's a new rumble
piercing the eerie silence.

- Popocatepetl is a
large stratovolcano

located very close
to Mexico City.

It's quite an active volcano.

- When Popocatepetl
erupted in 800 AD,

it destroyed nearly
everything in its wake.

Nearby settlements were
wiped out by hot ash flows

and mudslides.

There were fast-moving flows
of volcanic mud, water, ash,

and debris that
spread for miles.

It essentially
destroyed everything

within a 21-mile radius.

- Devastating eruptions

only happen roughly
every one to 2,000 years.

But unfortunately for what
remains of Mexico City,

it's about that time.

- Though there were
minor rumblings

here and there over the years,

the volcano was actually dormant

for much of the 20th
century, until the 1990s,

when it became active again,

occasionally shooting out
ash or spilling some lava,

reminding us that the threat
is still very much there.

- [Narrator] With a roar,

the volcano erupts

and a superheated flow
of gas, rock, and ash

wipe out all life
within 20 miles.

- The Torre Mayor is
outta reach of the lava,

but this kind of eruption
sends hundreds of thousands

of metric tons of volcanic
ash up into the air.

That can spread for
hundreds of miles.

- At large enough quantities,

this amount of ash can
actually blot out the sun.

In 1815, Mount Tambora
erupted in Indonesia,

spewing ash that was
so great in quantity,

it cooled the average
global temperature

by five degrees Fahrenheit
for three years.

- [Narrator] What's
left of most buildings

collapse in the aftershocks,

but the unshakeable tower
still stands strong.

In the aftermath
of the eruption,

a thick layer of
ash settles over it.

It looks harmless,

but soon, storm clouds
swirl overhead,

and the combination
could be the key

to toppling the
mighty Torre Mayor.

- Mexico City receives more
rain on average every year

than even London,

which is the city known
for its wet weather.

- Volcanic ash absorbs
rain like a sponge,

and then it dries to form
this cement-like sludge

that is even heavier.

- So if you have even five
inches of ash on a rooftop,

just a little bit of water
that's added to that ash,

and almost every roof will
collapse from that weight.

[water rushing]

- After 100 years
without maintenance,

all it takes is a few days
of crushing, uneven weight.

[debris crashing]

Now her bones are exposed,

and the pouring rain isn't
just relentless, it's mutating.

- Volcanic ash can turn
your run-of-the-mill rain

into acid rain.

So Torre Mayor isn't just
being smothered in ash,

it's being corroded
by acid rain.

- Once the roof is breached,

any additional corrosive element

is gonna have a much easier time

getting to the interior
of the building

and to those viscous dampers

that are holding
everything together.

- [Narrator] It's taken a
century to expose a weakness

in this marvel of
human engineering,

but will it be enough
to bring it down?

[tense music]

For nearly 100 years, the
Geneva Free Port protected

the rarest and most precious
treasures humanity left behind.

Now it's decaying
from the inside out,

a once mighty fortress
scarred by fire.

- It wasn't just a normal fire,
it was a superheated fire,

topping out at
over 1,000 degrees.

Steel loses about 50% of
its structural strength

at around 1,100 degrees.

So you can imagine how weak
it would be right about now.

- [Narrator] Despite
all it's faced,

the free port still stands,
but now winter descends,

bringing freezing temperatures
and swirling snow.

- Wet, slushy snow can weigh
anywhere from 25 to 50 pounds

per cubic foot, and
ice is even heavier,

weighing just shy of 60
pounds per cubic foot.

That's a lot of extra weight
and stress on a building

that's already been gutted
and weakened by fire.

- [Narrator] With a shudder,

steel snaps and cement crumbles.

- All the supports
and infrastructures

would be so weakened

that it crumbles
beneath the fallen roof.

The free port collapses
like a house of cards,

and just like that,
a lot of mankind's

most cherished
treasures are gone.

- [Narrator] It's now
reduced to rubble.

But what relic of mankind
still survives in the ruins?

[tense music]

- [Narrator] For 150 years,

Mother Nature has
worked tirelessly

to undo all that
mankind had built.

The famous St. Louis
Arch has collapsed,

and in Washington, D.C.,

all that's left of the Lincoln
Memorial is broken rocks.

But in Kentucky, there's
a secure compound

hiding beneath what remains
of a sprawling army base,

and it's designed to
survive any apocalypse:

Fort Knox.

- During the Great Depression,

Americans had to turn in
whatever gold they had

in exchange for paper currency.

When FDR took us off
the gold standard,

all of that gold
had to go somewhere,

and it had to be protected.

- Fort Knox was
basically America's bank.

What was inside
was the foundation

of our entire monetary system.

At one time, it was
said to hold more

than 4,000 tons of gold bullion,

worth as much as $400
million in today's currency.

- [Narrator] To protect
the nation's fortune,

Fort Knox was built to stand up

to any attempt to
breach its vault,

including a direct
nuclear strike.

- The vault's walls are made
out of four-foot-thick granite,

which are lined with steel,
cement, and fireproofing.

The door alone weighs 20 tons.

That's the equivalent of
three or four elephants,

and the entire thing
is buried underground.

- Fort Knox was impenetrable
when it was built in 1937.

They used the
strongest materials

available at that time.

- [Narrator] As technology
evolved, Fort Knox adapted,

adding layers of security
like an outer perimeter

with motion sensors, a
10-foot-high electrical fence,

virtual trip wires,
and landmines.

- It's got biometric
authentication.

It's got high-res
infrared vision cameras.

It even has seismic sensors.

- In 2009, the area was
hit with a brutal ice storm

that caused Fort Knox
to go without power

for an entire week.

Officials refused to
continue being dependent

on outside power after that.

- Fort Knox has 20 methane wells

found deep underground
near the base

to power all of its operations.

It becomes the first
energy-independent

U.S. Army base in America.

- [Narrator] A tangled
web of pipes and valves

once moved fuel from
nearby tanks to the fort,

like veins to a heart,
powering its independent grid.

In the time of people, the
system was closely guarded

and carefully maintained.

But now, it has
long since failed,

and its arteries have been
eroding for 150 years.

- Without maintenance, the
systems that power this place

are gonna corrode, and
that's gonna happen

because of the presence
of hydrogen sulfide,

which is in the natural gas.

- Hydrogen sulfide
is highly corrosive.

It can degrade metal,
making it brittle

and ultimately eating
it away entirely.

Some metals are, of course,
stronger than others,

but over decades or centuries,

even the most robust
metals are going to fail.

[gas hissing]

- [Narrator] Toxic
gas and leaking fuel

have been creeping through
cracks in the pipes,

coming up through the ground,
and saturating the area.

With just one spark, one jolt,

and Fort Knox's
impenetrable defenses

will be put to the test.

[tense music]

In New York City,

Lower Manhattan is no
longer a financial hub.

It's a watery maze of
streams and rivers,

overgrown and teeming
with animals.

- The wetlands of Manhattan
have reclaimed their territory

just like they were
thousands of years ago.

- Now this once-buzzing
financial district

is literally underwater.

What was once marshland
is marshland again,

with only some remnants
of man's achievements

poking up out of the muck.

- [Narrator] Once filled
with iconic skyscrapers,

the city's skyline
is nearly empty.

But even after every tower
has succumbed to the elements,

One World Trade Center still
stands above the wilderness.

It bears the scars of 250 years,

but it endures.

- After centuries of exposure,

the steel beams and
columns are badly weakened.

And even that concrete core,

the spine of the
whole structure,

has been quietly
cracking for decades.

It's been losing the fight with
Mother Nature inch by inch.

- [Narrator] The
collapse of other towers

and even her own spire

have wounded One World
Trade too deeply.

And 2.5 centuries after people,

with no maintenance or upkeep,

her mighty spine finally cracks.

- After hundreds of
years of high winds

and relentless decay, even this
giant can't take it anymore.

The top of One
World Trade Center

shears off at the 21st floor.

[building crashing]
[dramatic music]

- [Narrator] The
tower has fallen.

But will any part
of it be spared?

Or will it all
come crashing down?

[tense music]

- [Narrator] In Mexico City,

the strongest tower in
the country still stands,

while everything
around it has crumbled.

But acid rain has
been pouring through

its shattered roof for years,
eating away at its defenses,

including the viscous dampers

that have made it
earthquake-proof.

- The dampers are
still functioning

because they don't need power,

but the steel they're attached
to has become corroded.

- As steel corrodes, it expands,

cracking the welds,
loosening the bolts,

pulling the damper anchors
free from the frame.

The attachment points
are giving way.

[metal cracking]

- Imagine the dampers as joints

and the steel
framework as bones.

The bones are
starting to fracture,

which renders the
joints powerless.

- Now, all 738 feet
is truly vulnerable

for the first time.

- At this point,
after all these years,

it wouldn't even take a
massive quake to bring it down.

It's far from its former glory.

- [Narrator] The basin rumbles,

not with a powerful earthquake,

but a string of minor tremors.

[debris crumbling]

The ground rumbles,

and without those
dampers running,

the Torre Mayor sways and sways,

and eventually
topples over entirely.

[building crashing]
[dramatic music]

- [Narrator] The tower
finally succumbs.

Once hailed as one of the
strongest structures ever built,

now its body lies,
broken bones exposed,

to be reclaimed by the
jungle now growing unchecked.

Almost no trace remains
of the free port built

to protect humanity's treasures.

Deer, fox, and badgers roam

where masterpieces
once lay in vaults.

But inside one of the innermost
basement storage rooms,

there are some relics of
mankind that remain untouched,

and in some ways, in
better condition than ever.

Bottle upon bottle
of the finest wine.

- The Geneva Free Port
is said to hold around

three million bottles of
high-quality collectible wine,

and some of it is still good,
maybe even better than ever.

- Some wines are
actually made to last.

Cabernet sauvignon and
merlot, for example,

have high levels of
tannins and high acidity,

which means they age really
well, sometimes for centuries.

- And some wines have
lasted even longer.

In 2019, in Spain,

a 2,000-year-old
glass urn was found

in a Roman necropolis still
containing liquid wine.

- [Narrator] Once,
the most sought-after

vintages on the planet,

now these bottles wait for
drinkers who will never come.

[tense music]

[birds chirping]

In Kentucky, centuries
after people,

the most secure vault mankind
ever built still stands.

But fuel from its
long-dormant power plant

has been seeping through
the surrounding ground

and spreading like a virus.

- You've got gas escaping
out of the ground

and an environment

that's completely
overgrown with vegetation.

So you only need
one more ingredient

to create a truly epic
wildfire, and that's one spark.

[thunder rumbling]

- Kentucky ranks in
the top 10 states

for cloud-to-ground
lightning strikes,

averaging half a million
ground strikes per year.

That's over 1,400
strikes each day.

- [Narrator] A bolt of
lightning arcs toward a tangle

of brush, and it
bursts into flame.

What follows is
utter destruction.

- The flames are spreading

and eventually collide
with the leaking methane,

creating the mother of
all Molotov cocktails.

[explosion blasts]

- [Narrator] An explosion
rips through one side

of the abandoned fort,

and a fireball tears
through the empty columns.

But will it be able
to breach the vault?

[tense music]

- [Narrator] An explosion
has rocked Fort Knox

and a fire has
charred its walls,

but buried deep in the earth,

the vault built to
store America's wealth

still guards its treasure.

- This scene would
look like something

out of an Indiana Jones movie.

You would have
vegetation concealing

the remnants of human activity.

And if you looked carefully,

you might see a pile of
something shiny and gold.

- The thing about gold is that
it doesn't rust or oxidize.

It essentially never degrades.

If it ever is exposed
to sustained heat,

it simply melts and
then re-solidifies.

So Fort Knox could look
like it was flooded

by a river of gold.

It'd be like the lost
city of El Dorado,

except there's no one left
to go searching for it.

[tense music]

- [Narrator] Around the world,

the mightiest skyscrapers we
left behind have crumbled.

Only the ghost of
the Torre Mayor

haunts the flooded plain
that was once Mexico City.

- Torre Mayor had redundancies
built on top of redundancies,

but nothing is immune to time,

especially when nature never
stops testing the limits.

- [Narrator] The Sydney
Opera House is gone,

with no one to remember it.

- These buildings survive
because we maintain them.

They're not built to
last on their own.

So, without people, without
that constant upkeep,

these amazing structures are
eventually going to crumble

back into the earth.

- [Narrator] In New York,
the Manhattan skyline

has been reduced to rubble.

But at the island's
southern tip,

a reminder of humanity's
engineering prowess

still stands:

the remaining floors of
the World Trade Center.

- The bottom 20 stories
are still there.

They're practically
like a bunker,

half a million tons
of high-grade concrete

that can withstand seven
times the pressure

of regular concrete.

- That base isn't
going anywhere.

It may not be supporting
the mighty Freedom Tower

like it once was,

but what's left is still
very much a monument.

It's a symbol of
human ingenuity.

It is built to stand
the test of time,

even in a world without us.

- For these structures,
like the Freedom Tower,

the point was to be the
best we've ever built.

And even when
surrounded by ruin,

these towers are
still hanging on.

- Imagine New York City,

now, mostly forest.

Just green everywhere.

But this iconic tower
still looms over it.

If you're not getting
"Lord of the Rings" vibes

from this, I don't know
what you're thinking of.

- [Narrator] One by one,
humanity's footprints

are being wiped from the earth.

In spite of all of
our best engineering,

Mother Nature is
patient and unyielding.

After people, even
the fortresses

we built to last forever

eventually crumble into dust.

- We like to think that
we build for eternity.

But nature doesn't care
about concrete and steel.

Leave it long enough,

and even the strongest
structures will fail.

[tense music]

- Forever's a human idea,

and we forget that
Earth has its own clock.

And without us
here to fight back,

even our greatest
monuments become ruins.