Original subtitles

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- [Narrator] The world's greatest structures

push the boundaries of engineering,

all fueled by a constant desire to innovate.

- Without engineering there would be no modern world.

- [Narrator] Gigantic buildings, complex infrastructure,

and ingenious inventions.

- Engineering is the key that turns dreams into reality.

- [Narrator] Many of today's incredible achievements

rely on breakthrough technologies

first devised by ancient engineers.

- It's astounding how they achieved this.

- [Narrator] Early civilizations built

on an unimaginable scale and with incredible precision.

- They raised a bar for engineering

in a way that no one thought possible.

- These are some of the finest engineers in history.

- [Narrator] Redefining the known laws of physics

and dreaming up the impossible.

They constructed engineering wonders;

from colossal stadiums

to mighty waterways

and complex machines.

All with the simplest of tools.

- You cannot imagine the skills

people would've needed to build like this.

- [Narrator] By unearthing the mysteries left

by these ancient engineers

we can now decode their secrets.

- That so many of their creations still survive

is testament to their engineering prowess.

- [Narrator] And ultimately reveal how their genius

laid the foundations for everything we build today.

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The desire to be enthralled by spectacle

is as old as humanity itself.

The collective power of an event on a massive scale

taps into the human need for an exciting shared experience.

- Entertainment is vital for us as humans.

It's such an important part of a well-rounded life

to have that opportunity to relax,

to enjoy a period of time when you're not working

or involved in other things in your life.

- It nurtures culture, it promotes talent and creativity.

It relieves stress.

It really is one of the things that makes us human.

- [Narrator] The appetite for entertainment

has led to the construction

of some of the most impressive buildings in history.

- The grandeur of the buildings that we've constructed

to entertain ourselves says so much

about how much we value entertainment.

- [Narrator] Specifically when it comes to stadiums.

Roofless venues with tiers of spectator seating

surrounding an outdoor sports field.

- We're talking about tens of thousands of people

in one building.

Think of any other building that can do that.

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- [Narrator] Colossal structures, purpose built,

each with their own unique appearance,

attributes, and atmosphere.

- Stadiums nowadays are really complicated,

sophisticated bits of engineering and architecture.

- [Narrator] Widely known for its exterior,

Germany's Allianz Arena consists of

the largest membrane shell in the world,

with more than 300,000 LED lights

concealed behind its facade.

Making it possible to illuminate in any of 16 million colors

with a flick of a switch.

And the University of Michigan's stadium is recognized

as the largest football venue in the United States,

despite opening back in 1927.

Steel and wire mesh were used to create this behemoth,

holding an astonishing 107,600 spectators.

But the DNA of today's spectacular stadiums

has ancient origins.

- Stadiums are not in any way a recent phenomenon.

They've been part of our towns and cities

far longer than the Medieval cathedrals

or the railway stations of the Industrial Revolution.

- [Narrator] Many that have stood for millennia

are widely regarded as engineering masterpieces,

with one surpassing all others;

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the Coliseum.

A spectacle of design that combined innovative engineering

with cutting edge construction

to create one of the world's most iconic structures.

But this was far from the first stadium to be constructed.

Their history dates back more than 2,500 years.

Like many other historical engineering feats,

the concept and design for stadiums

was first developed in Ancient Greece.

- The first stadiums arrived in the 8th century BC,

and we're looking at the skill and speed

and strength of athletes.

- If we go to the Greek world,

the earliest stadiums that we know about

are for athletic races, foot races.

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- [Narrator] With the first stadium of its kind

found in the ancient sanctuary of Olympia.

A 630-foot-long athletic track

sandwiched between two massive embankments of earth.

- The Stadium of Olympia is a remote place.

It's very quiet, but at the same time,

there's almost an electric sense of history there.

You know that there have been really important events

on that track.

- [Narrator] Constructed almost 3,000 years ago

and home to the very first Olympic Games

in 776 BC.

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- You don't need to replace in your mind

an enormous lost building as you do

in so many ancient sites,

just here it's the banks.

And you can imagine them being filled with people.

- [Narrator] A relatively simple design,

but the site at Olympia was the inspiration

for countless other ancient Greek stadiums

across the country,

as well as over the Aegean Sea in present day Turkey.

Wherever they were constructed,

the stadiums were filled to capacity

with avid sporting fans.

(crowd cheering)

The growing popularity of athletic events

called for the construction of larger venues.

Simple earthen banks would no longer suffice.

Greek engineers had realized the importance of the audience

and began designing spectator-oriented stadiums.

- This is the next stage in the evolution of stadiums,

built with the spectators in mind.

They had to create benches all the way around it.

It was an immense feat of engineering.

- So we are now at a point where

we're to stone architecture,

not just simple earth banks around an open field,

but a built environment.

It's a much more considered,

much more architectural setting.

- [Narrator] Rows and rows of specially carved stone.

Fortunately, the Mediterranean region

had abundant supplies of limestone and marble,

among the chief building materials in ancient Greece.

But while limestone was relatively easy to work with,

marble came with immense challenges.

- Marble is heavy and it's difficult to work.

You can carve it to a very beautiful finish

if you've got the right tools and the right skill

and it costs you a lot of money.

- [Narrator] Even excavating the luxurious stone

demanded engineering expertise.

Ancient Greeks began by carving deep grooves into the rock

with hammers and picks

and relied on an unusual quarrying technique

to then split the marble away from the rock face.

- Quarrying marble is one of the most difficult things

that anyone can do.

They had several techniques.

One of the things they did was used wedges,

which they hammered into the natural fissures in the marble.

- [Narrator] The wooden wedges were soaked in water,

and as they became saturated, they expanded,

forcing the stone to split along its natural faults.

- Those wedges made the marble crack away.

And from there they could shape the marble

into the benches they needed for the stadium.

- [Narrator] The stone masons relied on a combination

of point, flatheaded, and rounded chisels

to carve and smooth the surfaces.

Such tools and techniques

enabled the Greeks to construct venues

large enough for the growing crowds.

Grand stadiums to host the ancient sporting events,

all inspired by the ancient Olympic games held at Olympia.

(crowd cheering)

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Since its resurgence in the late 19th century,

the hosting of the modern Olympics

has attracted enormous prestige.

- The revival of the modern Olympic games

was really significant for humans

because it created this event

that the whole world could get behind.

- And they've turned from what was already quite a big event

to a kind of epoch making global megastar event today.

- [Narrator] Those that won the right to host

the Olympic games were required to construct stadiums

to host a variety of large scale events

and the huge crowds that would inevitably follow.

- Countries coming together to do something great,

to want to demonstrate athleticism,

but actually to want to demonstrate engineering prowess.

- [Narrator] Munich's Olympiastadion was built to serve

as the flagship venue for the 1972 Olympics.

Boasting an ethereal canopy of 8,000 glass panels

and over 270 miles of steel cables.

While Montreal's 541-foot high tower

is the tallest incline structure in the world,

leaning over the 1976 Olympic stadium

at an angle of 45 degrees.

Spectacular sporting venues designed for the games

standing as tribute to the ancients' ingenuity.

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The popularity of Greece's sporting events continued to grow

along with the variety of contests

that the crowds came to applaud.

Eventually a new distinct type of arena

began to appear in cities across their civilization.

- The ancient Greeks loved horse racing

and they built horse racing courses called hippodromes.

- Whereas the foot races in Olympia

had been within a rectangular track,

the Greeks now extended their races

into more exciting horse races.

And so for the hippodrome you need a curved end

that the horses can race around.

- [Narrator] As seen with the modern reconstruction

in Athens, the locations were generally dictated

by the terrain and were dug into a hillside.

The excavated materials were used

to construct the embankments for spectators,

with tiered seating along the two opposite lengths,

as well as around the curved end of the track.

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Greek engineers had created the ideal environment

to host their sporting competitions.

But one ancient civilization

would adopt the Greek hippodrome structure

into their own society:

The Romans.

- The Romans took the idea of the Greek hippodrome

and in classically Roman fashion, they improved it.

- [Narrator] Both structures were designed

for equestrian events.

However, while the hippodromes

were the largest sporting structures created by the Greeks,

the Romans took their magnitude to the next level

with the circus.

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But race tracks of this grand scale

required careful planning and calculations.

- They were very well built.

Precision architecture, precision craftsmanship,

blocks fitting together beautifully,

really solid choice of materials.

And that didn't happen by accident.

They used excellent tools on site

to survey what they needed

and measure and put things into place.

- To make all of this possible

the Romans needed some engineering tools

and their most important was the groma.

This was used for measuring straight lines and right angles,

both of which were fundamental to all Roman architecture.

- [Narrator] A long staff supporting horizontal cross pieces

mounted at right angles on a bracket,,

each with a plumb line hanging vertically at the end.

Once positioned, the surveyor would use

the aligned plumb bobs as a visual guide

for laying out markers in a near perfect straight line.

- If two of the lead weights are in line

with a man with a stick, you've got a straight road.

And then to build the next section of straight road

you move the groma to where the man with a stick is.

He goes a bit further along,

and then you've got another section of straight road.

And on and on.

And you can design road. You can design buildings.

It's an incredible invention.

- [Narrator] A device that much

of Roman construction hinged on.

By the 6th century BC,

the first circus was constructed in Rome

and became a roaring success.

They would go on to be built throughout the Roman empire,

including Israel, Egypt, and Great Britain.

Chariot races had become the Superbowl of their day,

but they weren't the only event circuses held.

- Other things the Romans enjoyed

included parades, wild beast hunts, executions.

We imagine all of those things also happened in the circus.

- [Narrator] And one contest for the blood thirsty mob

was fast becoming the favorite of Rome:

Gladiator games.

- While the circus was really good for things

like chariot racing, because they happen along a long path,

with two people fighting

they don't need to travel very far whilst fighting.

So it didn't really suit itself

to what was becoming Rome's favorite sport.

- [Narrator] The Roman engineers had to devise

a more practical arena,

designed specifically for huge numbers of people

facing an enclosed central space.

Dating back to the first century BC,

the Romans set out to build a new type of sporting venue

for gladiator combat.

- What you need for that is a piece of ground

a bit bigger than a boxing ring.

And you need to be able to look down on the action.

So they needed purpose-built arenas,

and they turned to an oval arena

where gladiatorial combat happens.

The amphitheater, like a double theater.

- [Narrator] Amphitheaters were a triumph

of the ancient world,

with some still standing today.

- If you want to experience what it really is like

to be in a fully built amphitheater,

then the best one to go into is the one in Pompeii.

- [Narrator] Constructed in 70 BC,

the Amphitheater of Pompeii is recognized

as the very first to be built out of stone

in the Roman world.

443 feet long and 341 feet wide,

it could hold up to 20,000 spectators.

The largest of its kind.

- It's got a deep oval arena with a high parapet wall

so that the people down in the arena floor,

the combatants, are separated from the seating,

and then ranked seating in a big bowl all the way around.

So you could imagine several thousand Pompeiians

cheering in the seats.

- [Narrator] But the Roman engineers had to devise a way

not only for the crowd members to access their seats,

but for the gladiators themselves

to enter and exit the arena floor.

Their solution?

An internal corridor

that ran the entire circumference of the amphitheater.

In order to construct such a passage way,

the ancient Romans needed a key architectural element:

the barrel vault.

- An arch is a very stable and effective shape

for creating structures that are very strong.

So a barrel vault is essentially a series of arches

connected together to create a corridor.

- [Narrator] The weight of the earth and stone above

is absorbed by the key stones in the center of the vault

and distributed evenly over the entire span of the arches

and then down into the side pillars.

This allows the pillars to bear enormous loads.

- Barrel vaults are a really fantastic feature

that we kind of have seen all the way through architecture.

We've seen them in churches.

We've seen them in historical buildings.

They just see them everywhere.

They're just a prominent feature.

And I think it's maybe because how beautiful it looks,

but also how important it was as a load bearing structure.

- And one of the great things

about using arched construction in these stone arenas

is that you can move a lot of people around the complex

by using tunnels in the underside of the thing

to distribute them around the area of seating.

- [Narrator] The amphitheater's design

was optimal for crowd control,

built to withstand thousands of spectators

coming in and out.

But there was one force that the Roman engineers

hadn't planned for.

After slumbering for centuries,

on the 24th of August 79 AD,

Pompeii began to shake.

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Mount Vesuvius had reawakened.

- When Vesuvius erupted the sky would've gone black,

the noise would've been deafening.

It would've been truly the most terrifying thing

that anyone had ever experienced before.

And they all fled for their lives.

- The pumice, the dust, the hot gases swept over people.

It basically incinerated them in situ

and it covered Pompeii with this volcanic dust,

which entombed it for centuries afterwards.

- [Narrator] Buried by volcanic ash,

the amphitheater survived

úthe eruption of Vesuvius almost intact.

But not all structures are so fortunate

against the forces of nature.

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As natural disasters continue to shake the modern world,

it's up to engineers to ensure

that buildings are designed

to have the best possible defense.

- Engineers are always looking to advance the designs

or materials they're using

to make their structures more resilient

to natural disasters.

- [Narrator] Buildings are now designed

to sound engineering principles.

To withstand all foreseeable loadings

and extreme conditions throughout their lifespans.

And as new technologies and components are embraced,

ever bigger, more amazing, and safer structures

take shape across the globe.

But whether it's a skyscraper, stadium, or school,

these buildings all still rely

on a single material for their strength.

One made hundreds of years ago,

with properties that make it especially valuable

for natural disaster-resistant buildings:

Steel.

- Steel is a great material to use for a number of reasons,

but definitely when it comes to disaster protection.

- It's strong, it's durable,

and of course it's not flammable.

But also, steel is so critical

because it's ability to resist buckling.

And that gives you a confidence in designing with it

and building with it.

- [Narrator] Still used to create some of the world's

most distinctive buildings.

Completed in 2008,

the Beijing National Stadium was at the time

the largest steel structure ever constructed.

The only catch?

It's located in one of the world's

most active seismic zones.

In order to earthquake-proof the 91,000-seat stadium,

the design was critical.

- So the inside bowl of the stadium

is not connected to the outer structure.

And also the bowl itself

is separated into different segments

that all have their own stabilizing system.

- Therefore, if there was going to be an earthquake,

bits would actually just move

and it would flow and adapt more

rather than be still and actually collapse.

- [Narrator] An incredible feat of engineering

to conquer the most destructive of natural disasters.

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By the beginning of the 1st century AD,

amphitheaters could be found across the Roman Empire.

- Amphitheaters become a symbol and badge of Romaness,

wherever you get a Roman settlement in the Western empire,

it will have probably an amphitheater.

- [Narrator] Their size and intricacy

often reflected the importance of the city or town

in which they were situated.

But without a doubt, the sprawling empire center was Rome.

- At its peak in 400 AD

Rome consisted of a million people

and no other city would surpass that

until Victorian London in the 19th century.

- We're talking about the largest,

one of the most carefully planned cities

in the ancient world.

- [Narrator] Gleaming white marble temples and palaces,

bustling markets, theaters, and bath complexes,

with an extensive network of aqueducts

supplying fresh drinking water throughout the city.

- Ancient Roman must have been like nowhere else on Earth.

The Romans created a sprawling city

peppered with incredibly large and sophisticated structures.

- Then, in 80 AD, Rome became home

to something the world had never seen before.

The largest building the Romans ever constructed.

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The Coliseum.

- You cannot miss the Coliseum.

It is a goliath amongst structures.

It's still an anchor within the city of Rome.

- If there's one structure that still survives,

that makes you truly appreciate

the genius of Roman engineering,

without doubt, it's the Coliseum.

- [Narrator] The ultimate stage for gladiator combat.

Yet, this was much more than an arena

of death and suffering.

The Coliseum was a carefully engineered

entertainment complex,

and one of ancient Rome's greatest accomplishments.

- This is an arena built on a monumental scale

to exacting standards using supreme Roman engineering.

- The planning that went behind the construction

of the Coliseum would've been immense.

The Roman engineers understood the need

for appropriate foundations for a building that size.

- [Narrator] After reaching a firm clay bed,

a gigantic donut-shaped base was laid out,

39 feet deep and over 1,700 feet in circumference.

Foundations strong enough to support

the largest freestanding amphitheater in the world.

(suspenseful music)

The story of the Coliseum dates back almost 2,000 years,

at the end of the infamous Emperor Nero's reign in 68 AD.

- The emperor Nero was a notorious tyrant.

He built enormous monuments to himself.

The money that came into Rome, he largely spent on his self.

He had what's called the golden palace of Nero.

And as part of this palace, he had a pleasure lake.

This is monumental selfishness,

and that grated against the people of Rome.

So he became deeply unpopular.

- [Narrator] Nero was eventually declared

an enemy of the people by the Senate

and committed suicide shortly after.

- The problem with Nero's departure

is that there are a number of short-lived emperors

who wrestled to take control.

And this created an era of real instability in Ancient Rome.

So a stabilizing influence had to be found.

- [Narrator] Around 71 AD, a new emperor,

named Vespasian, came up with a plan

to restore the city of Rome to its former glory.

- He was determined to reaffirm trust

from the Romans in their leaders.

Vespasian wanted to get the people of Rome on his side

and the way he did that was to build

the ultimate place for entertainment.

- [Narrator] He began construction on an amphitheater

unlike any that came before,

right on top of Nero's pleasure lake.

But a building is only as good

as the material that binds it together.

Many ancient mortars were notoriously weak.

But Roman ingenuity solved the problem

with a new mix that beat mortar hands down.

They called it opus caementicium.

We call it concrete.

- You mix sand and mortar and water and aggregate,

and you can then lay it into any shape you want.

So it's material that's cheap and versatile

and quick and super strong.

- [Narrator] Roman concrete's phenomenal resistance

and durability against elements of nature

made it the perfect material for the Coliseum's foundations,

as well as the structure itself.

But such an ambitious construction project

would need more than just the right material

to ensure its success.

- When you look at the Coliseum,

one thing you notice very clearly

is that it's a freestanding enormous structure.

It doesn't have a lot of buttressing around the side.

And that is because of the genius design they used

to create this amazing piece of engineering.

- Rather than relying on the landscape for support,

this was a free standing structure.

They built everything from scratch.

- [Narrator] In order to form their great monument,

the Romans had to turn

to several key architectural innovations,

including one that changed the construction playbook:

The groin vault.

- A groin vault is really taking the arch to the next level.

If you consider two barrel vaults,

which are corridors of arches coming together,

when they intercept at the middle

and you've got this cross of arches coming together,

it means that each arch is supporting the other arches.

And you have this amazing open space underneath,

but very, very stable and self-supporting.

- [Narrator] With the combined strength of four posts,

groin vaults require less buttressing

and therefore are an even sturdier structure.

- So it's this vaulting technology that allows the Romans

to build freestanding entertainment buildings

like theaters or amphitheaters.

And you see it really perfected at the Coliseum.

- [Narrator] A combination of barrel and groin vaults

ran around the Coliseum's arena,

supporting the seating areas above

while allowing for high ceilings,

and ultimately the monumental stadium.

And the Coliseum's exterior consisted

of 240 gigantic arches,

each up to 23 feet high.

- Every tier has arches marching around this building.

Aesthetically it creates a real unifying effect.

Structurally it creates greater solidity.

- The use of arches in the construction of the Coliseum

was also important because it created natural entrances

and a variety of them.

And that meant that Roman society,

which was divided into numerous classes,

could all have their own entrance.

- [Narrator] A well-organized, durable super structure

with a capacity of over 50,000.

(suspenseful music)

In 80 AD the four-story amphitheater was finally completed.

- A decade after construction began,

it was Vespasian's son, Titus,

who had inherited the throne of emperor.

And under him, the thing was completed.

- [Narrator] Titus held a hundred-day-long

inaugural games where spectators came out each day

to watch hours of entertainment.

- The opening games at the Coliseum were spectacular.

And they went on for days and days under the Emperor Titus.

These games were enormous ongoing jamborees.

- So they had gladiatorial fights

and wild animal hunts and skirmishes.

It was the ultimate opening ceremony.

- [Narrator] 5,000 animals are believed

to have been slaughtered in a single day

during the opening games.

- The Coliseum is really a temple to violence in many ways,

essentially what thrilled people was the spectacle,

the jeopardy involved in life and death.

- [Narrator] But the Coliseum is believed

to have gone one step further

with an event bordering on the impossible:

Mock naval battles with real floating ships.

- Historians have been debating this idea

of holding mock naval battles

in the Coliseum for generations.

And one thing that is certainly true

is that it would definitely have been possible.

- [Narrator] Some argue that moving such a vast amount

of water in and out of the amphitheater

would've been unfeasible, even for the Romans.

Yet, if the claims are to be believed,

then the water would have to have been

no higher than around five feet

to avoid spilling over into other rooms and corridors.

requiring more than a million gallons of water

to flood the arena up to that depth.

- Not just having hard ground

for these blood thirsty battles,

but actually flooding the Coliseum for warship battles.

It blows your mind to think

how they may have even done that.

- [Narrator] It's also thought that the Coliseum

could be flooded for sea battles in the morning

and drained quickly enough

for gladiator combat in the afternoon,

a feat that would've required serious hydraulic engineering.

- We know it's possible because of

the extraordinary Roman ability to manipulate water.

There were 11 separate aqueducts,

all bringing water directly into Rome.

The water was certainly there

and they could have got it inside the Coliseum.

- [Narrator] A large tunnel running under the walls

of the Coliseum is thought to have fed water

into a labyrinth of channels,

all leading to the center of the arena.

An extensive hydraulic system

that could have delivered enough water

to flood the arena floor.

And some believe they have uncovered a system

used to get the water out.

- They use their engineering ingenuity

to remove the water as well.

So they actually built four large storm drains,

which they pulled to drain the water from the arena.

- The size of the drains and their ability to empty

into the cloaca, the main sewers for the city,

suggests that you could almost certainly

have emptied it within the course of an hour.

- [Narrator] The water is believed to have flushed out

at a rate of up to 280 gallons per second,

equal to more than 10 of the most powerful fire hoses

blasting all at once.

If confirmed, then the Coliseum would've been

one of the world's first multipurpose stadiums.

A feature that engineers continue to explore,

with some stadiums

pushing the boundaries of what's possible.

When Tottenham Hotspur FC embarked on its mission

to replace its old stadium,

it aimed to create a truly world class multi-use venue

capable of staging a variety of major sporting events,

each requiring different sized and surfaced fields.

This called for a feat of innovative engineering

never seen before.

- Amazingly you can turn the natural grass pitch

into a synthetic grass pitch

to transfer it for use from soccer into American football.

- [Narrator] Its full-sized football pitch

has been engineered to split into three sections

and retract into a storage area beneath the south stand,

revealing the synthetic American football field beneath it.

Mounted in three enormous trays,

the 9,800 ton pitch weighs roughly as much

as the Eiffel Tower, yet takes just 25 minutes to retract.

- Fans who experience one sport may not ever know

that they can experience different sport

in the same stadium and that is great engineering.

It's great innovation.

- [Narrator] The world's first dividing,

retractable grass football pitch.

(suspenseful music)

The Coliseum guaranteed an unforgettable show

for anyone with a ticket.

But the Roman engineers also had to consider

the comfort of the paying public.

- It's hot in Italy in the summertime.

And if you're sitting there all day on marble seats,

watching gladiatorial combat and getting excited

and cheering, you're really gonna get uncomfortably warm.

- [Narrator] The engineers had to come up

with a way of shading the audience from the sun.

- Their solution was to build a kind of awning,

a retractable roof over the Coliseum,

made from canvas taken from similar designs to ships sails.

- [Narrator] Known as the velarium,

this enormous retractable canvas awning

would be a welcome feature

to many state-of-the-art sports stadiums even today.

And recent research has provided a good idea

of what it must have been like.

- We know from marks and holes in the masonry

right up at the top,

that there were places for huge wooden spars to jut out.

And it was across those, using a complex system of rigging,

that these sails were spread,

providing shade for everyone below.

- [Narrator] But raising the velarium

was a complicated procedure

and demanded a team of specialist operators.

- It's been estimated that these sails

weigh as much as 24 tons.

That was an extraordinary feat of power and teamwork

to get these hoisted and to get them set.

And it made perfect sense that the only people

qualified to manipulate this huge awning were sailors.

- [Narrator] More than a thousand experienced sailors

were drafted in from the Roman fleets,

stationed in barracks around the corner from the Coliseum.

- They know how to pull on ropes

and handle canvas in the wind.

Crucially, they can also respond

to orders over a distance, right?

They'd be very reliable, disciplined body of men

to get this very complicated, quite fragile,

piece of heavy engineering up into the air.

- [Narrator] The velarium was an incredible

piece of engineering.

Not only protecting the audience members,

but also enhancing the spectacle on the arena below.

- The velarium extended its sail-like canopies

into the area of the Coliseum,

but it didn't cover the whole area.

It left an open oval in the middle.

- So you can imagine this big gap in the middle

with the natural sunlight coming through

acting like a spotlight onto all the things

which were happening in the arena.

- [Narrator] A phenomenal ancient achievement,

no one would surpass the Coliseum's retractable roof

for almost 2,000 years.

(suspenseful music)

Then, in 1989, construction finished

on the Rogers Center in Toronto, Canada,

a 52,000 seat stadium

with a feature unlike anything seen before.

- The Rogers Center in Toronto

is really a spectacular example

of what is possible in engineering.

This stadium had the first fully retractable roof.

- [Narrator] Covering an area of around 340,000 square feet,

the roof is made of four massive steel panels

and weighs a total of more than 9,800 tons.

One panel is fixed

and the other three slide on a system of steel tracks.

- You might think retracting the roof off

to be quite a long operation taking hours and hours.

Well, it only takes 20 minutes.

And that's the power of some innovative engineering.

- [Narrator] Driven by more than 70 10-horsepower motors,

the roof panels slide at a whopping rate

of 71 feet per minute.

Impressive engineering used to create

the world's first fully retractable roof.

With its scale and impeccable design,

the Coliseum was the envy of the ancient world.

Then several years after its grand opening,

Emperor Titus's younger brother, Domitian,

decided to improve the amphitheater further.

- The Romans were always on a constant quest

to improve whatever they created.

And that certainly applied to the Coliseum.

- [Narrator] It was completely remodeled

with one of the most significant changes

made away from the view of the spectators.

- They invent effectively an undercroft

underneath the floor of the arena,

where there were designed sets and stages.

- [Narrator] An underground complex

on a scale, never seen before in Rome:

the Hypogeum.

This subterranean labyrinth worked as a backstage area,

allowing the games to be mounted on an even grander scale.

- The Hypogeum allowed people to be moved very quickly

to different parts of the floor of the Coliseum,

by means of tunnels and trap doors and such things.

You could see it as a kind of backstage area.

The kind of thing that a modern theater might depend on.

- [Narrator] As the crowds begged for blood,

hundreds of gladiators took their positions,

blacksmiths prepared weapons,

and arena slaves hurried to keep the show moving

on the sands above.

- It would've taken an actual army

of people behind the scenes.

It would've been quite miserable. It would've been dark.

It would've been hot. It would've been smelly.

- [Narrator] And it wasn't just people

that inhabited this torch-lit underworld.

The Hypogeum was also home to hundreds of exotic animals,

imported from all over the empire to be killed for sport.

Most were kept in sturdy pens,

but transporting them up to the arena above

would require an engineering innovation.

- How do you get extremely heavy animals

up to the floor of the Coliseum?

- [Narrator] Deep under the arena there are patterns, holes,

and grooves in the walls,

clues to curious machinery

housed in the Coliseum's underworld.

- One of the most interesting design features

of the Hypogeum was a number of lifts,

which were used to hoist up animals and props,

whatever it might be, up onto the stadium floor.

- [Narrator] Some of the earliest examples of lifts

seen in the ancient world.

- You can see in those Coliseum lifts,

the beginnings are something that one day

would be parallel to our passenger lifts.

- [Narrator] dotted throughout the Hypogeum,

there is evidence of as many as 28 ancient lift systems,

where beast handlers herded animals into them

before being cranked up to the arena.

Each lift is thought to have had cap stands

with four rotating arms

that would've been used to lift up to 600 pounds each,

all the way to the arena floor, 23 feet above.

- Having all of these lifts at their disposal

meant that they could put on

the most extraordinary spectacular shows.

Just imagine the impact of dozens of lions

suddenly appearing out of nowhere.

(crowd cheering) (lions roaring)

- [Narrator] But even with hundreds of laborers

working away, lifting these weights

would still have been extremely strenuous.

Either the lift operators or ropes themselves

would eventually reach breaking point.

The Roman engineers had to find a way

to keep the show running smoothly.

- These primitive lift systems that very likely relied on

a simple engineering innovation that we still use today,

the pulley, the reason why it's so effective

is because it massively reduces the amount of force,

the work you need to do to lift a load.

- [Narrator] Adding a pulley splits the weight evenly

between the two sides of the rope.

And another pulley changes the direction of the force.

Easier to pull down than up.

With one pulley attached to the cage,

it feels half the weight.

Attaching two pulleys to the cage

makes it feel like a quarter of the weight.

- The more pulls you have, the more effective that is,

and the less kind of muscular human effort is required.

- [Narrator] With these ancient lift systems in place

men and beasts could emerge

all onto the Coliseum arena floor.

The spectacle seen by the screaming crowds

was now more impressive than ever before.

- There's that element of mystery,

not knowing what's coming up from that lift.

So there's also that sense of the additional entertainment.

- You could just imagine the energy in that stadium

with the number of people in there

and watching the drama unfold right before your eyes.

It would've been an incredible thing to experience.

- [Narrator] Unforgettable gladiator battles,

with men and beasts appearing as if from nowhere.

This was the Coliseum in all its glory.

The backstage lifts operating in the Coliseum

set the foundation for the development

of modern stage technology,

raising the possibilities of arena and stage production.

But these brilliant contraptions

go far beyond enhancing entertainment in the modern world.

Now ubiquitous throughout modern industry,

lift systems have also transformed

urban architecture and landscapes.

- Without lifts we wouldn't have the high rise buildings

that we rely on in cities.

Lifts are a critical part of engineering today,

and they have been for years.

- They move millions of people

and millions of tons of goods all the time.

And we'd struggle to operate without lifts.

- [Narrator] Continuing to carry further and faster

than ever before.

Today, one of the world's fastest elevators

is installed in the 128-story Shanghai Tower,

the second tallest building in the world.

It rises almost 1,800 feet vertically

through the skyscraper,

traveling at a speed of 46 miles per hour,

nearly twice as fast as Usain Bolt.

- Very few people would realize

that almost 2,000 years beforehand,

the Romans had settled on essentially the same technology,

even if it was fit for a very different purpose.

- The possibilities of what engineers will create

in the future around lift systems is just never ending.

There will always be new heights

that engineers will take us to.

- [Narrator] Ancient engineering brilliance

that helps keep the world running smoothly.

Stadiums have come a long way from their humble origins,

with the ancient Greeks and Romans

recognized as the true stadium pioneers.

Many of their ideas and techniques are still utilized today

in some form or another.

Found in designs far larger and more ambitious

than those that came before.

As humans continually strive to create

an engineering wonder as symbolic as the Coliseum,

one of the ancient world's grandest

and most spectacular engineering achievements.

(dramatic music)