Original subtitles

NARRATOR: How could the ancients build colossal structures

in less time than we can construct the biggest buildings

of today?

How could the ancient Egyptians produce thousands and chariots

with assembly line precision?

Why did the Romans create a massive, underground industrial

hell where thousands of slaves never saw the light of day?

Monuments more colossal than our own, ancient superweapon

as mighty as today's, technology so precise

it defies reinvention--

the ancient world was not primitive.

Their marvels are so advanced we still use them now.

Travel to a world closer than we imagine, an ancient age

where nothing is impossible.

The biggest builds of today are the result

of mammoth engineering projects, huge structures that

define the modern era.

But who are the greatest engineers of all time?

Could there have been building projects

just as impressive in ancient times?

The Romans were not only the biggest and strongest power

of the ancient world, but they were also the most

technologically advanced.

They made amazing buildings and military machines.

They were so ahead of their time that it's only recently

that modern engineers have been able to replicate

their techniques.

And one of the Romans most incredible

discoveries-- concrete.

It's only in the last 100 years or so

that concrete has come to play such a large part

in our architecture.

But it's actually a rediscovery.

Amazingly, the Romans were using it for their biggest builds

over 2,000 years ago.

The science of concrete was perfected by the Romans

thousands of years ago.

And when the Roman civilization fell, that science was lost.

And the most amazing example of this Roman engineering miracle

is to be found here at Caesarea, on the coast of present day

Israel.

Unbelievably, they built a huge harbor made of concrete,

and it was one of the biggest artificial ports

in the ancient world.

Imagine how our cities and ports might have developed

if this knowledge hadn't been lost.

It was another 2,000 years before mankind could replicate

this technology.

When the technology was rediscovered,

it essentially shaped the modern world.

Everything around us relies upon the presence of concrete.

NARRATOR: But what's so special about concrete?

It can be shaped and molded.

With concrete, the Romans could make arches, vaults, and domes.

This was revolutionary.

If you imagine the times before concrete,

you're relatively limited to what it was you could dream up.

But then the minute that you could create

these man-made stones in essentially any shape you

wanted, architects, they were free to dream.

They were liberated, and they did dream.

NARRATOR: And at Caesarea, they dreamed the impossible--

using concrete underwater.

This was something extraordinary.

In modern times, underwater concrete

has only been used for about 150 years,

but the Romans were using it 2,000 years ago.

This sounds impossible, but here it at Caesarea, the Romans

made the impossible possible.

I'm standing amidst the ruins of the impressive artificial

harbor in Caesarea.

This would have been an incredible sight

in the ancient world.

NARRATOR: The harbor was certainly an engineering

marvel, over a million cubic feet of concrete embedded

in the sea.

Just the thought of building a man-made harbor

was a sign of the audacity of the Romans.

And then the decision to use concrete

was even more astonishing.

And the man behind it?

Herod, the Romans' puppet king of Judea.

He's often thought of as an evil tyrant,

but because he was in league with the Romans

he was able to commission some of the greatest mega-builds.

King Herod needed a large harbor.

There were no natural places to anchor ships.

He decided to build one from scratch.

The harbor itself was unbelievably huge, big.

Nobody could see such a big structure worldwide.

It was the largest structures on Earth at the time,

90,000 square yards.

That's a huge area.

The port extends on either side of where I'm standing,

to the south over 1,500 feet long,

on the northern side about 1,000 feet long.

You have to think of about 40 acres

or 30 football fields are comprised within the two arms

projecting forward.

He created a water break that was 180 feet wide.

Huge.

You could have a highway on top of it.

It extended deeply to the sea, almost half a mile

into the sea.

NARRATOR: Herod wanted to build a huge harbor to rival any

in the world, and that's despite the lack

of a good natural harbor at this site.

This was because he wanted his province of Judea

to be the main trading route for East to West.

His incredible harbor could accommodate 300 ships.

It dwarfed anything found here before or since.

See part of the bottom port over here.

The actual breakwater of the port of Caesarea is underneath,

and it's sunken down about 5 meters

beneath the surface when it extended twice the length out

into the sea.

NARRATOR: The concrete harbor was so impressive

that King Herod built a new palace for himself

on the waterfront.

And the port became the catalyst for a great trading city

and a new capital for Judea.

This port was a commercial center, a hub.

There's a massive market in the Western half

of the Mediterranean.

The Roman senators, they want the goods from the Middle East

and from the Orient.

This became one of the key harbors that brought

those goods from East to West.

NARRATOR: But how did the Romans build this harbor?

What was the magic ingredient that they

used to make the concrete set?

And how did they lay concrete underwater?

It's only recently that we have uncovered the truth.

At this concrete factory in Austin, Texas,

they have the ingredients prepared.

There are seven ingredients in marine mix concrete--

quicklime, clay, seawater, sand, fly ash, large aggregates,

and animal blood, in this case, pig blood.

NARRATOR: One theory is that blood was

used to strengthen the mixture.

But the key to underwater setting lay elsewhere.

They developed a kind of mortar that had extraordinarily

good lime in it.

And that made it strong to begin with.

But the real key is the chemical reaction

that happened when they added pozzolano sand to their mortar.

NARRATOR: This special kind of sand came from volcanic ash.

It made the concrete so durable it could harden underwater.

Luckily, Thanks to Mount Vesuvius in Italy,

the Romans could find this sand in abundance.

The fact that Mount Vesuvius was over 100 miles

away wasn't going to stop them.

So they had to ship over this volcanic sand

in enormous amounts.

We're talking about 44 ships with a 400-ton capacity,

without that, this artificial harbor could not

have been built. So it's something

that the Romans develop and perfect,

and it allows them to pour this and have

it harden in the saltwater.

NARRATOR: Marine concrete hasn't been made

in this way since Roman times.

Is it possible that it can be recreated today?

We work with concrete all the time.

We're going to try today to recreate

ancient marine concrete, like used at the ancient harbor

of Caesarea.

NARRATOR: For the Romans to discover 2,000 years ago

that volcanic ash would have this effect

was an enormous technological leap.

And this was done on an industrial scale.

Hundreds of slaves would have been used to carry, mix,

and pour the materials.

It must have been a massive operation.

This ancient concrete mix is going underwater.

It will be ready for testing in 30 days.

We're going to find out if this ancient concrete recipe really

works.

NARRATOR: The ancient empires of the Mediterranean

depended on sea power for military dominance

and for trade.

The Romans were no different.

In fact, they always took things to another level.

They had to have the best ships, the best crews,

and to go with them, the greatest, most up-to-date

ports.

It's not so different today.

The major cities of the world are ports.

90% of all the world's trade is still transported by sea.

In ancient times, great cities such as Carthage and Alexandria

grew up around their ports.

But the Romans were able to do what for everyone else

was impossible.

They could build a port like no other.

It was built bigger, and it was built to last.

And at Caesarea today, the massive 2000-year-old concrete

jetties can still be seen just under the water.

As a diver, what you see just below the surface of the water

is huge construction.

The poured concrete is intact.

And as you swim along, you'll see actually the imprints

of the wooden framework into which the concrete was poured.

NARRATOR: This is remarkable.

This concrete is 2,000 years old,

and it's still intact on the seabed.

How did the Romans lay this concrete underwater?

It's an engineering marvel.

Specially made wooden barges were partly

filled with concrete and floated into position, then anchored.

More concrete was then poured in.

So you set those up, you pour in the concrete.

And as it settles and hardens and solidifies,

you can sink it down to the bottom, where it would harden

and be able to withstand the force of the sea.

And they were going to build these in sections.

It's just a massive enterprise.

NARRATOR: This process, repeated again and again,

eventually led to the massive concrete jetties

rising from the sea.

And the giant jetties would probably still be in use today

if they hadn't been built on a seismic fault. Over the years,

earthquakes have taken their toll.

Still, the concrete has survived.

Modern concrete routinely shows signs of degradation

after just 50 years.

The strength of concrete can be tested.

And at this engineering company in Austin, Texas,

they have a special machine to do just that.

Basically what we do is we put a concrete cylinder

in the press, and apply a load, and see how much compressive

force it can take.

NARRATOR: New concrete like this holds out well.

Ooh!

NARRATOR: If they had a similar cylinder of Roman concrete,

they could precisely measure its strength.

In the nearby concrete factory, a mix of Roman concrete

has been left to harden.

And now the time has come.

How has the special Roman mix of underwater concrete fared?

Well, to me this is amazing, that this block of marine mix

concrete actually formed.

I didn't think it was going to form like this.

And you know, the crazy thing about this

is that this concrete gets stronger over time.

And it's only been 30 days hardening.

NARRATOR: This is ancient technology

at work, underwater concrete 2,000 years ahead of its time.

It's impossible to believe that this marine mix concrete

sat under water and hardened.

It's as hard as modern concrete.

NARRATOR: But exactly how hard is it?

How does Roman marine concrete hold up to modern testing?

For the first time, the engineering workshop

has a sample and will test the pressure it can withstand

in PSI, pounds per square inch.

That technology is a couple thousand years old,

and I'd be surprised if it got up to 200 or 300 PSI.

NARRATOR: Soon it becomes clear that after just 30 days

setting, the Roman mixed concrete

is bearing up remarkably well.

Anything beyond 300 PSI would be astonishing.

This came in at nearly 400 PSI.

For an ancient technology, that's incredible.

NARRATOR: With every week, the concrete

will get stronger and stronger.

This concrete mix was 2,000 years ahead of its time.

And that's without all the modern machinery

used in the industry today.

We're making modern concrete right behind me now.

It's impossible to think that all of this modern equipment

is needed to replicate what the ancient Romans were doing 2,000

years ago.

NARRATOR: Many of the biggest builds of the modern world

are factories and places of industry.

Even food, which used to be made in the home,

is now produced on an industrial scale.

In ancient times, could they have had factories like this?

Surely impossible.

But these strange ruins on a hillside in southern France

have a remarkable story to tell.

For years, they were a puzzle, but now history

is being rewritten.

We normally think that it was the Industrial Revolution that

gave us the modern idea of factories.

And before that, we had cottage industries.

However, we've now got to rewrite our understanding.

NARRATOR: The mysterious ruins are at Barbegal,

near the town of Arles.

And the clue to what went on here

lies above, beyond the hillside.

Here we find something spectacular.

We're in Southern France at Barbegal,

and this is a Roman aqueduct.

But it's unlike any Roman aqueduct you've seen before.

NARRATOR: What makes that so special is

how it was put to use.

The water from this aqueduct served a very special purpose.

What's so significant about this site

is that there were 16 mills powered by water

right along this hillside.

A huge series of water wheels.

This is something that's totally extraordinary.

We haven't seen the like until today

with modern hydroelectric systems.

This is a huge undertaking.

They actually turned a natural hillside

into a vast watermill system.

This is a really massive mechanical operation,

and it worked.

NARRATOR: The Romans didn't invent the watermill.

The ancient Greeks were the first to use them.

But nothing like Barbegal had ever been built before.

Together, these waterwheels comprised one of the biggest

builds of the ancient world, a waterwheel super factory

in the 2nd century AD, which has never been matched since.

And that's despite waterwheels remaining

in use for another 2,000 years.

It wasn't until the age of steam that the mechanics

of waterwheels were surpassed.

But not only was Barbegal massive,

it was also highly efficient.

It was much more advanced than any waterwheel technology that

followed it.

Many waterwheels, like this 17th century mill at Hereford

in England, are powered by water hitting the bottom or middle

of the wheel.

If we had a higher drop what we'd do

is we'd be bringing the water in over the top

and have an overshot shot wheel, so the water

fills all the buckets and turns it around.

More efficient, but you need to have that big a drop of water.

NARRATOR: Without a steep incline,

a stream can still power a waterwheel.

But at Barbegal, the Romans made use of the high drop.

The water pouring down onto the wheels, 66 gallons per second,

made each of these wheels 2 and 1/2 times more efficient.

But it's not just the mills here that were an engineering

marvel.

Getting the water to them was a seemingly impossible task.

Between the aqueduct and the mills was the top of the hill.

What the Romans do is they actually physically

cut a channel into the top of the hillside,

so the water can be fed through, and then

it can hit the top of the mill with absolute force

and then charge down 65 feet to the bottom,

creating a huge amount of force and momentum.

NARRATOR: The massive cutting was made through solid rock.

And it shows the incredible ambition of the Romans.

For them, when it came to building,

no obstacle was too big.

What's really impossible, just think about Barbegal.

Somebody had the vision to say, we'll capture water

six miles away, build an aqueduct,

stick it through a mountain, and then we'll

build a whole set of steps of water wheels

to harness all the energy--

16 watermills all stacked up.

The scale was immense.

This was able to put out about 4 and 1/2 tons of flour

every day.

NARRATOR: But what was all this flour for?

Today's mega bakeries use machinery

on an industrial scale to produce vast amounts of bread

for our towns and cities.

Why at Barbegal was the huge miling complex needed?

We know there were at least 12,500 people living in Arles,

and then some more military on top of that.

It looks like the wheels of Barbegal

produced enough bread to feed the entire population.

NARRATOR: Keeping people fed was all a part

of the Romans' grand plan.

Military might alone doesn't hold an empire together.

Very interestingly, there is no point

in having an empire if your people are either subversive

or starving.

So of course the way to keep them onside

is to keep them well-fed.

NARRATOR: During Barbegal's peak years,

the vast Roman Empire was growing at a breakneck pace,

bringing people together into urban centers,

keeping them under control, civilizing them.

It was all part of how the empire worked.

A city could be fed.

The people were then free to work, to make goods.

Goods equals wealth.

Wealth equals power.

A water wheel-- the power of the Roman Empire.

NARRATOR: But the empire didn't go on growing forever.

One theory as to why the Roman Empire eventually declined

is that it had so much slave labor there was no incentive

to embrace new technology.

Barbegal is important because it shows the opposite.

It's a water-powered factory.

I think when people learn about Barbegal,

they're always shocked and amazed.

Today, we think about factories, we

think about industrialization, we think about modern times.

But here the Romans are showing us

what they were able to achieve on a grand scale,

on an industrialized scale 2,000 years ago.

I think it's rightly earned a reputation

as being the greatest concentration

of mechanical power in the ancient world.

It's phenomenal.

NARRATOR: Remarkably, this hugely important

archaeological site has only really been fully understood

in the last few decades.

And it's been a revelation.

Before this, no one imagined such a place could exist.

Is it possible there could be other sites like this, which

have yet to be discovered?

The Barbegal mills are a real success story.

As a historian and archaeologist,

you're constantly thinking, maybe,

just maybe there's another example like this that is just

waiting to be found.

And what's really interesting about them is that, in a way,

this is the Industrial Revolution 16

centuries before the Industrial Revolution officially happened.

NARRATOR: Throughout the centuries,

warfare has driven technology.

Great scientific breakthroughs have been made in our quest

for new means of destruction.

Defense is a huge industry, and is responsible for some

of our biggest builds.

But could there have been an ancient military factory as big

as those of today?

This is the Joint Systems Manufacturing Center

in Lima, Ohio.

It's the home of the Abrams tank, 70 tons of imposing

military might.

All tanks for the US Army are built here.

During World War II, it mass produced tanks

at a phenomenal rate.

Victory in Europe depended on it.

It's still one massive factory with a highly skilled

workforce.

It's great knowing that you're building the best product

in the world, and soldiers are safe,

one of the best-built tanks in the world.

This is the first time that I've been on a tank.

And I have to say, it's a real thrill.

I mean, up here you really get the most incredibly commanding

view.

I'm a cavalry man at heart, and he's very

much like being on a horse.

NARRATOR: In many ways, the tank is the modern equivalent

of an ancient fighting chariot, a mobile,

state-of-the-art fighting force.

But it's also a command center,

just like chariots were mobile platforms or artillery

on the battlefield.

It's not infrequently said, and I've often said it myself,

that the chariot is the ancient tank.

What it does is provide mobility.

NARRATOR: The fighting chariots of the ancient Egyptians

were the meanest machines on the battlefield.

But were they factory-made, like the tanks at Lima?

It's almost impossible to believe,

but over 3,000 years ago, the great Pharaoh Rameses II

had his own huge factory for the state-run production

of these fighting machines.

We have evidence of Rameses' chariot factory

both archaeologically and in tomb paintings.

And what we can tell is it was on a massive scale, state mass

production just like this tank factory.

Rameses demanded chariots, masses of chariots.

They were needed for a battle, a big battle, the Battle

of Kadesh, the greatest chariot battle

that the world has ever seen.

NARRATOR: In 1274 BC, Kadesh was the culmination

of the incredible mass production of chariots

under Rameses II.

And it was here in the desert of modern day Syria

that the Egyptian army clashed with the other superpower

of the day, the Hittites.

With thousands of chariots on each side,

this was chariot warfare on an unprecedented and massive

scale.

That's an awful lot of chariots on the field.

And you imagine them swirling around in the dust.

It's a thick dust storm, and it's a real dogfight

as they're all trying to outmaneuver

each other and the archers to pick off their opponents.

NARRATOR: But how could so many chariots

have been made, and where?

The factory that produced the Egyptian chariots must

have been massive, big enough to supply

the huge numbers of chariots needed for the war

with the Hittites.

And a possible site has been identified at Pi-Ramesse

in the Nile Delta.

What we have is tables for something like 480 horses,

which means 240 chariots.

We have a training ground, and we

have a place which is said by some people

to be a chariot factory.

NARRATOR: The site on the Nile has yet to be fully excavated.

But one thing we know for sure is that, remarkably,

the factory used an assembly line, just like the tank

factory at Lima.

So here we are at the assembly line.

And you can see tank after tank after tank stretching back

there.

You're taking preformed pieces.

You're bringing them to an assembly plant,

and skilled workers are putting things together.

It is almost impossible to imagine

that over 3,000 years ago the manufacturing processes,

the systems for making military hardware would be the same

as they are in the 21st century.

But they were.

It was the same principle-- assembly line factory work.

Henry Ford is known as the creator of the production

line in the 20th century.

But 3,000 years ago, impossible to believe,

the Egyptians did the same, an assembly line

that churns out relentlessly chariot

after chariot after chariot.

NARRATOR: On the floor of the tank factory,

the individual components come together.

They're state of the art and made by specialist teams.

It was just the same in the chariot factory.

First, the body of the chariot--

lightweight wood curved into shape by steaming it.

Just big enough for two standing men.

The undercarriage was a fixed axle and a central pole

made by one artificially bent piece of wood.

Quite a large wheelbase directly beneath the body

to keep the chariot stable.

The frame for the horses is also made of bent wood,

and it attaches to the end of the pole.

You can't have a chariot without wheels.

One quick assembly, a deadly mobile fighting machine.

NARRATOR: The Egyptians understood the importance

of using the perfect materials and imported wood especially,

in particular ash.

Even today, one specialty builder

of sports cars in England still uses ash

just as the ancient Egyptians did.

This is the Morgan Car Factory, where skilled craftsmen have

been assembling cars in this way for over 100 years.

Ash, of course, would be ideal for a combat vehicle,

a chariot, for the same reasons that we use it.

It's not only extremely strong, it's lightweight.

The lighter you could make a structure like that,

the easier the horses could pull it, the more flexible

it would be, and the more effective fighting machine.

Being flexible, it can act as a shock absorber.

It's the same with us here in Morgan.

The frame will flex and bend with the chassis,

and this all adds to the road holding and the handling

of the cars.

NARRATOR: The factory here makes around 100 tires

a month, handcrafted with skill and precision.

Rameses II needed chariots in their thousands.

The fact that his chariots could be mass produced

was in itself a source of wonder and terror for his enemies.

Rameses' systems were so advanced, so

efficient in producing the great numbers of military vehicles

that he needed, it's almost impossible

to conceive that factories of this scale

existed 3,000 years ago.

But they did.

NARRATOR: Some of the most iconic buildings

ever constructed are huge cathedrals, such as Notre Dame

in Paris and St. Paul's in London.

But incredibly, one of the biggest builds in history

is a cathedral from ancient times.

In 6th century Constantinople, when the magnificent cathedral

of Hagia Sophia rose from the ground,

it was as if the impossible had happened.

This is the Hagia Sophia.

It is one of the most impressive architectural constructions

in the world.

It exerted an influence for 1,000 years

after its construction.

"Hagia Sophia" means holy or divine wisdom in Turkish.

And the building is the supreme masterpiece

of Byzantine architecture.

And for almost 1,000 years, it was the biggest cathedral

in the whole world.

NARRATOR: Still standing after 1,500 years,

with minarets added at a later date,

this was an incredible build with techniques centuries ahead

of its time, a Roman Christian cathedral that was a revolution

in architecture.

This is such an amazing space.

You've got something that's intact,

something that's constructed in the 6th century AD.

And the thing is, it's hard to get a sense of how

massive this space is, because there are so many openings.

There's so much light.

It's almost impossible to imagine what people thought

of it when they first saw it.

They must have thought that they were looking at something

impossible.

They wouldn't have understood how it stayed upright.

A lot of people thought that God himself

was holding the building.

That's how special it was.

NARRATOR: And this was exactly the intention.

The man behind it, the Emperor Justinian,

needed to assert his political power.

To do this, he wanted to be linked with God

in the most visible way.

He wanted it to represent not only his greatness on Earth,

but God's greatness in heaven, and to draw

that link for people to say "I am

God's representative on Earth."

NARRATOR: In the 6th century, the Roman Empire

was based in Constantinople, modern day Istanbul,

but the empire was fading.

Justinian knew that if he didn't make his mark

in some grand way, he would be just a footnote in history.

He wanted to be great.

He was determined that as well as being something massive,

his cathedral was going to be something completely new.

So he didn't go to the master builders of his age.

He went to mathematicians.

He depends upon these experts of math, and geometry, and science

to go in a new direction, to create something that no one

had ever seen before.

To understand it, we need to start with the dome.

NARRATOR: The dome is the most impossible achievement.

It's 102 feet across and 180 feet high.

It's huge.

It's broader than the dome of the Capitol building.

And that was built 1,300 years later.

But the most amazing thing is that the dome doesn't

seem to be resting on anything solid.

Essentially, you have this massive dome,

which seems to just rest lightly on these 40 windows.

So it's something that's ethereal, almost light

about it.

And for a dome to be built on a square base rather than a round

one was something completely new.

For the Romans to achieve this was truly remarkable.

These four piers are essentially building supports.

And in the Hagia Sophia, they're huge.

They were built to support the dome.

Well, four arches were built on top of the columns.

Then the spaces in between were filled with masonry.

They fill in the upper corners of the space,

and so form a circle of support for the dome.

This was a giant leap in architecture.

It must have been incredible then, because today it

still looks awe-inspiring.

NARRATOR: Hagia Sophia is huge, about 65,000 square feet.

But the speed of its building was impossible, too.

Normally, cathedrals took decades to build.

The construction of Notre Dame hundreds of years

later took over a century.

And just the dome of the Capitol building took 11 years.

This is a large structure that's

built in a mere five years.

That is incredible.

To give a modern comparison, the Burj Khalifa in Dubai,

which is the tallest building in the whole world,

took six years.

And that's with all the modern technology that we now have.

That is a tribute to Justinian's vision to make this engineering

miracle happen.

NARRATOR: Some of the biggest builds of the ancient world

were factories and places of industry.

And just like today, some of the most impressive of these

were built because of our insatiable desire

for precious metal.

The Romans' need for copper and silver

brought them here, to Rio Tinto in Spain.

And for 2,000 years, the mine held a dark secret deep

beneath the surface.

This is the Rio Tinto mine in the heart of Andalusia

in Southern Spain.

It's absolutely vast, almost 20 square miles.

The first people to start exploiting metals

in these hills were over 5,000 years ago.

In Roman hands, this mine became the single greatest mining

complex in the whole of the ancient world.

NARRATOR: And it was here in 1919

that an astonishing discovery was made--

a huge wooden wheel buried deep in the ground.

Further investigation revealed that it was almost 2,000 years

old.

But what was it for?

The answer is almost impossible to believe.

A clue was found here, at a gold mine in Dolaucothi in Southern

Wales, a similar wheel and well-preserved enough

for a scaled down replica to be made.

Remains of that wheel were found 150 foot down,

so far down that it's reasonable to expect that more

than one wheel were used.

And this is a replica of what one of those wheels

may have looked like.

NARRATOR: It became clear that the wheel was

used to lift water, to prevent the mine from flooding.

Water from the bottom was scooped up, and then fell out

at the top, into a channel that drained it away.

And someone must have stood deep underground turning the wheel.

What a horrendous job, a human hamster in near

pitch black conditions.

The Romans were masters of waterwheel technology.

But with a waterwheel, normally moving water turns the wheel.

At both Dolaucothi and at Rio Tinto what the Romans did

was turn that concept on its head.

They used manpower to turn the wheels,

and then the wheels moved the water.

Move the water, drain the mine, miners work.

Genius.

NARRATOR: But could a large wooden wheel really

have been any use here at Rio Tinto?

This mine is massive, and the Roman shafts

went deep into the earth.

We now know that at Rio Tinto, the use of these wheels

was taken to impossible extremes.

Underground caverns carved by hand from the earth,

and inside--

eight pairs of huge water wheels,

powered by slaves walking the wheels.

To a modern engineer, it would seem incredible.

To the ancients, it must have seemed impossible.

But it was an impossible task that the Romans

faced and mastered.

This was ancient engineering on a massive scale,

and it made the impossible possible.

NARRATOR: The wheels were probably

prefabricated and constructed within the mine.

Building a whole series of these huge water wheels

underground is almost beyond belief.

Today, it would be incredible.

2,000 years ago, simply impossible.

As the slaves trod the wheels, the water

was channeled from one pair to the other,

eventually rising over 100 feet before being drawn

to the surface by a huge Archimedes screw.

This wasn't hell on Earth.

It was hell deep within the Earth--

dark, hot, and working with toxic, mineral-soaked water.

The slaves who operated these waterwheels had the worst

job in the whole mine.

Their life expectancy once they got down here

was about 12 to 16 months.

It was that poisonous, and they were constantly

coated in the water.

And when they finally died, which they inevitably did,

the Romans didn't even bother taking their bodies

to the surface.

NARRATOR: But whatever the terror of the wheels,

they were truly an ancient wonder,

an incredible, fantastic construction.

Unbelievable structures built with techniques thousands

of years ahead of their time, the biggest builds

of the ancient world were as astonishing and awe-inspiring

as anything built today--

a world of wonder, of terror, and of the impossible made

real.