Original subtitles

♪

narrator: A lost villa buried near the colosseum,

epic engineering secrets of the pantheon's design,

astonishing mysteries of ancient aqueducts.

These, and other new discoveries,

are shining a light on seven wonders of ancient rome.

These iconic megastructures

set the benchmark for roman ingenuity.

How were they built?

And what secrets do they still conceal?

Today investigators use pioneering archaeology...

This is something much more precious.

There's writing on them.

...And forensic technology...

Blank: Reading the papyrus has been the biggest challenge

that I've had in my professional life.

Narrator: ...To decode the mysteries

of ancient rome's world famous icons.

Across the empire,

these massive monuments define a global superpower.

How do ancient engineers

overcome the incredible challenges

of building bigger than ever before

across multiple continents?

We reveal how the most powerful empire on earth

enters a new age of engineering achievement

to build the seven wonders of ancient rome.

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

captions paid for by discovery communications

the seven wonders of the ancient world

span three continents

and thousands of years of history.

But 2,000 years ago,

a new generation of engineering wonders

rises to take their place.

♪

how do the romans match the engineering might

of earlier ancient civilizations...

♪

...And ensure their monuments still stand today?

♪

a clue lies in the first wonder --

the colosseum.

A giant complex at the heart of the ancient city of rome.

Its sheer size rivals

the largest of the original ancient wonders --

the great pyramid of giza.

The colosseum is an arena of death and magic,

of potent spectacles with the power to sustain an empire.

Buried within its walls are clues that reveal

this is much more than just a theater.

Giordano: The colosseum still strikes our heart today.

You can still feel the same feeling

that the roman spectators felt at the time

of the performances.

♪

today, teams of experts are exploring deeper

than ever into the heart of the building,

to solve the mysteries behind its construction

and how it holds infamous gladiatorial battles.

♪

and each year,

archaeologists uncover new evidence of life

in and around the monumental arena.

Now excavations for rome's new metro line

that runs right past the colosseum

reveal something extraordinary.

Workers discover the remarkable remains

of a luxury villa.

They investigate the findings

to reveal it belongs to a military commander.

It features 14 rooms, complete with stunning frescos

and mosaic floors.

As work continues on the metro,

archaeologists hunt for new evidence

of this ancient civilization

to reveal how the hidden secrets of this vast ruin

ensure the colosseum still stands today

when so many of the original wonders of the ancient world

have fallen.

♪

concealed under the colosseum's skin

is a complex system of pillars, arches, and vaults.

They spread the colossal load of nearly a quarter

of a million tons of stone,

allowing this building to tower 157 feet

above the streets of rome.

In the stadium, space for up to 80,000 spectators,

big enough to hold the super bowl.

Built into the arena floor,

a subterranean maze of tunnels and chambers,

the secret domain of the empire's deadliest servant --

the gladiator.

The colosseum and the men who fight in it

are the most iconic symbols of the roman empire.

♪

even today, the colosseum is an impressive structure.

The original ancient wonders,

like the lighthouse of alexandria

and the temple of artemis,

have long since disappeared.

But incredibly,

this roman wonder's 157-foot-high walls

still stand after nearly 2,000 years.

Giordano: This building is iconic as it represents

the evolution of the roman empire

from its rise through its fall.

Narrator: Yet despite its crumbling exterior,

the colossal colosseum still mystifies archaeologists.

♪

1,900 years ago, it looks even more magnificent.

The stone, now weathered after two millennia,

would have shone brightly polished.

In the perfect archways, statues of marble and gold

trumpet the glory of rome.

Its walls stretch nearly 2,000 feet around the outside,

rising higher than any other structure in the city.

♪

this is the biggest single building

ever created by the romans.

♪

but how do ancient roman engineers

make this monumental structure so robust

it still stands today?

A clue lies hidden in the bay of naples

to the south.

♪

here, underwater archaeologists discover the remains

of an ancient roman town called baiae.

Brushing away the silt reveals a stunning mosaic

buried inside the remains of an opulent villa.

Archaeologists send loose fragments of the mortar

that holds it together

to mineralogist mauro francesco la russa.

Mauro believes these ruins survive thousands of years

because the builders use super strength materials --

concretes and mortars unique to the bay of naples.

[ speaking italian ]

mauro discovers the secret of the materials' strength

using a high-power electron microscope.

The volcanic rock creates an incredibly durable material

when mixed with lime.

[ speaking italian ]

narrator: The discovery of the super strong concrete

not only builds this ancient underwater town,

it also transforms the roman empire.

This wonder material is the key

to ensuring rome's expansion and position

as a new global superpower.

It allows engineers to construct the empire's finest monuments,

including rome's first wonder --

the colosseum.

But the colosseum isn't just famous

for its monumental structure.

♪

the giant amphitheater carries a message from rome's leaders --

follow us and we will keep you thrilled.

The empire's ancient wonders glorify the strength

of roman imperial power.

And the stars of the show are the gladiators.

Very little is known about these legendary warriors.

But hidden in the vaults and columns of the colosseum

are tantalizing clues to their origins.

These warriors are the biggest attraction in the empire.

Inside the arena, they became the stars of a true spectacle.

Deep within the maze of brick walls under the colosseum

lies a secret entrance

to their violent and bloodthirsty world,

a doorway connecting a 180-foot-long tunnel

that brings the fighters into the arena.

2,000 years ago, this leads to rome's

fabled fighting school, the ludus magnus.

Standing right next to the colosseum,

this is the breeding ground

of the most powerful roman propaganda tool --

the gladiator.

♪

these fearsome warriors

champion the ferocity of roman combat skills,

a show of deadly force for all to witness.

But there's a mystery.

No gladiator bones

have ever been discovered at the colosseum

to tell us more about the lives of the gladiators.

Are they just the empire's disposable thugs?

♪

fabian kanz investigates these fearsome warriors.

He has unearthed something astonishing --

the only gladiator bones that have ever been found.

They are discovered in the grounds of an amphitheater

that once sits on the edge of the empire

in what's now modern-day turkey.

Fabian thinks the men, far from being disposable thugs,

are treated more like valued athletes.

♪

and fabian discovers that these incredibly rare bones

can tell him even more about the lives and diet

of these men.

Chemical traces of the food they eat

builds up in their bones.

To analyze the chemicals in these gladiator skeletons,

he grinds a bone sample into a powder and adds it to a liquid.

When he sprays the liquid into a flame,

it will burn with a signature color,

a fingerprint that reveals the chemicals

locked inside the bone.

Strontium is a mineral similar to calcium

and strengthens bone.

Fabian thinks the strontium-rich gladiator bones

are a clue they are fed a special diet.

These new heroes of the colosseum put on a spectacle

that shows off the might of the empire

and rouses patriotic passion in its citizens.

The astonishing arena becomes a showcase

of overwhelming imperial power,

bolstered by the incredible strength

of the roman concrete and mortar that builds it.

These features ensure the colosseum still stands

as an epic engineering masterpiece.

Today it is regarded as a true wonder of ancient rome.

But beyond theatrical spectacle,

the romans need practical engineering solutions

to help their cities function.

How does the empire supply its people

with the basic amenities to survive and thrive?

Does the next roman wonder, the aqueduct,

hide a secret to the one

of the colosseum's biggest mysteries?

And can gruesome discoveries

in the ancient city of herculaneum

reveal what devastates the population?

♪

♪

narrator: For five centuries,

the roman empire is the mightiest on earth.

And one extraordinary wonder stands at its heart,

the colosseum.

The colossal arena matches and even surpasses

the greek's list of original ancient wonders.

The colosseum stands as an icon of imperial power,

and its mighty construction is possible

thanks to the romans use

of super strong concrete and mortar.

But the secret of roman success

is not just in the materials its engineers use.

The romans maintain power throughout their empire

with constant innovation.

They keep their burgeoning cities under control

by providing basic amenities like fresh water.

♪

secrets to how they do this

lie hidden inside ancient rome's second wonder --

the pont-du-gard aqueduct.

A vast megastructure in the roman province of gaul,

now southern France.

It is a monumental icon of roman technology.

Spanning the river gardon, it carries water over 30 miles.

Built in the 1st century a.D.,

it is considered the tallest roman construction in the world.

This ancient wonder still stands

with help from the super strong roman mortar.

♪

aqueducts represent the pinnacle

of their hydraulic engineering prowess.

Engineers construct aqueducts across the empire,

but they are critical to the functioning of rome.

These giant structures

cross hills, valleys, and packed cities.

How do engineers conquer these formidable obstacles

to build these massive structures?

To keep water flowing from springs surrounding rome,

engineers dig trenches around hills,

and cover them with bricks and earth.

♪

to overcome high mountains,

they dig tunnels right through them

with shafts in the roof for ventilation.

♪

to cross ravines and valleys,

they funnel the water through lead pipes,

pushing it up the hill on the other side.

And to channel the water into rome,

they build mighty arched aqueducts,

some over three stories tall.

Today, in the heart of rome, the magnificent trevi fountain

is still supplied with water from an ancient aqueduct.

But in the first century,

there could be another astonishing use

of aqueduct water.

The colosseum, ancient rome's first wonder,

plays host to an array of deadly championships.

But one colosseum legend is cloaked in mystery.

Are giant sea battles staged inside this arena?

Higgins: The colosseum was a real showpiece,

so I think it's not improbable at all

that the romans would hold such a sea spectacle.

Narrator: How can this stadium possibly be filled with battleships?

There's a clue buried right next to the colosseum --

a three-foot-wide tunnel that runs right beneath the walls.

♪

archaeologists believe that it may feed into a labyrinth

of strange, shallow channels --

channels that lead to the center of the arena.

Could these be the remains of a gigantic hydraulic system

with the power to flood the colosseum with water...

♪

...So the emperor can watch full-blown sea battles,

the ultimate display of roman might and ingenuity?

♪

the legend of the colosseum's sea battles

comes from a single ancient text.

It describes the arena flooding in a matter of hours.

How could this be possible?

High up in the mountains outside rome,

valerie higgins investigates this mystery.

She starts at one of rome's famous aqueducts,

the aqua claudia.

It once channels waters 46 miles into the ancient city.

Higgins: We want to understand how much water could go through it.

We want to understand how it delivered water into rome.

How difficult is it for the romans to fill an arena?

Narrator: Valerie works with adriana morabido,

an expert in roman subterranean tunnels.

Higgins: Along here, we can see the level of the water going along.

Maximum half a meter of water,

and then the rest was just empty.

Obviously, it was going down by gravity, not by pressure.

Narrator: Valerie wants to work out whether this aqueduct

could supply the 3 1/2 million gallons of water

needed to fill the colosseum,

as the legend describes.

What we would like to do

is measure the height of the aqueduct,

and then measure it in another place, as well,

so we can work out the gradient.

The slope of the tunnel floor will help them calculate

how fast water flows into rome.

So here is 110, and there is 87.

So we have a 23 centimeters' difference in 9 meters.

But what they find is a very gentle slope,

a drop of just 9 inches in 30 feet.

[ beeping ]

the water here would flow far too slowly

to fill the colosseum to nearly five feet

in just a few hours.

Higgins: It's an extraordinarily large arena.

It isn't filled very high.

It's only filled to like a meter and a half.

But nevertheless, it's really hard to imagine water

coming through here filling the colosseum.

But valerie believes the aqueduct

may not tell the whole story.

She thinks there may be a crucial piece missing

from this complex puzzle of roman plumbing.

♪

multiple aqueducts, 11 in total,

channel freshwater directly into ancient rome.

Valerie's theory is that when the colosseum is built,

a huge water tank is added somewhere near the amphitheater.

The tank stores enough water to flood the colosseum in one shot.

Beneath the amphitheater, the network of circular channels

distributes the stored water quickly

and evenly into the arena floor,

ready for a spectacular sea battle.

Then, four huge drainage channels

opened to flush the water away again

in time for the next games.

♪

but if a storage tank that holds 3 1/2 million gallons of water

is the key to filling the colosseum,

where is it?

Valerie goes on the hunt

with the help of dr. Mateo baroni,

they track the route of the aqueduct through urban rome.

Near the colosseum,

they discover the partial remains

of a much larger structure.

Could it be the missing piece of the jigsaw?

Higgins: We have some remains of a monumental fountain.

What is interesting about the monumental fountain

is there was a water storage unit in it.

Narrator: The water storage tank that once feeds the fountain

is gone.

But valerie thinks it would have been big enough

to hold the volume of water required to fill the colosseum.

It's six meters difference between here and the colosseum.

It's very steep going down here.

It descends quite fast.

You could get a big, hydraulic pressure from here

that would push the water into the colosseum very quickly.

So I think it's a feasible proposition.

♪

narrator: Thanks to the ingenuity of roman water engineers,

the colosseum stages spectacles

that become legendary across the expanding empire.

The romans' technical innovations,

like hydraulic engineering and power over its people,

are secrets to their success.

They allow the empire to expand across continents

and build enduring monuments

that outlive the original seven ancient wonders.

But how far from rome does the empire stretch

and how does the roman army meet its match?

A clue lies in northern britain

with the romans' next ancient wonder --

hadrian's wall.

And in the heart of rome,

despite the empires advanced construction skills,

one of the most incredible wonders

has all but vanished.

How?

♪

♪

narrator: Rome's seven wonders are incredible sights to behold.

Stunning monuments that hide ingenious technical innovations.

They are the equal of the seven original wonders

of the ancient world.

Romans built their wonders to last.

And rome's third wonder is no different.

♪

hadrian's wall,

an astonishing ancient megastructure.

A mighty 73-mile-long man-made barrier of stone.

Like all of rome's wonders, it's built to last.

By the first century a.D.,

the roman empire expands across the mediterranean,

north africa, and crosses europe into britain.

The roman army appears an unstoppable force.

So why build a wall here?

And how does the construction of this gigantic wonder

ensure the empire's dominance in britain?

♪

hadrian's wall is the largest of rome's great wonders.

It splits the island of britain in half

from east to west, coast to coast.

The man behind the wall is the great emperor hadrian.

But its story is shrouded in mystery.

Collins: Hadrian's wall isn't written about

by very many roman authors,

so we don't ultimately know

what the romans thought hadrian's wall was for.

Narrator: Archaeologists once think

the wall is a symbolic statement of rome's power.

♪

now, new excavations by teams 500 strong

are discovering the wall's original layout.

And it reveals a more forbidding purpose.

In 125 a.D.,

roman engineers build hadrian's wall

with four million tons of solid limestone blocks

creating the biggest structure rome ever builds.

Its wall is up to 10 feet thick, standing as tall as three men.

From mighty stone towers every third of a mile,

soldiers keep watch 24/7.

And gigantic forts hold almost 10,000 troops to keep guard.

♪

what can the construction of this ancient wonder

tell us about who the romans face in this distant land?

♪

hadrian's wall gives teams of archeologists

a huge opportunity to uncover new insights

into how the mighty empire builds big.

Archeologist rob collins has studied hadrian's wall

for 20 years.

He believes this ancient wonder

is rome's greatest engineering achievement.

Collins: It's very easy to be wowed by the colosseum in rome.

But actually if you think of logistics,

that's a piece of cake.

Hadrian's wall is a much bigger logistical construction project.

Narrator: Today rob explores a section of the wall

at remote spot called steel rig.

Collins: What we see with hadrian's wall

is when the romans have that choice,

and you have a dramatic windswept crag,

the romans will build the monument

on the front edge of that crag,

so it really exaggerates the height of the wall.

Narrator: As well as building on top of huge cliffs

to make their walls seem bigger,

the romans dig vast ditches beneath it.

Collins: When you add those together,

hadrian's wall is much more of a defensive monumental barrier.

♪

narrator: The mighty roman army invades britain in 43 a.D.

After 80 years of fighting, they control most of the island.

Britain is supposedly at peace in 117 a.D.

When emperor hadrian comes to power.

But this vast monolithic wonder tells a different story.

Collins: This north facing crag is actually telling us

who the monument is being built against.

They're building it on behalf of the people to the south,

who are the residents of the province of britannia.

And we can see that they're trying to keep out

those peoples to the north,

who we traditionally call barbarians.

♪

narrator: These barbarians are

the native people of northern britain --

ancient iron age tribes of fearsome warriors.

But surely they are no match for the mighty roman army.

♪

the answer could lie one mile south of the wall,

at vindolanda.

Here hundreds of archaeologists work on an ambitious project.

♪

they dig up an entire roman fort

built just a few years before hadrian's wall.

The excavations here reveal evidence of fierce fighting.

Andrew birley is the site's lead archaeologist.

Birley: Vindolanda offers us an opportunity

to see exactly what's going on in this landscape

just before hadrian's wall is being built.

Narrator: During a recent analysis of previous finds,

the team uncovers something unusual --

a small piece of leather cut into the shape of a mouse,

perhaps a child's toy dropped

while fleeing from a fierce battle

or a soldier's idea of a practical joke.

The mud layer at vindolanda

is a time capsule of roman relics

with coins from hadrian's time

and even a 2,000 year old wooden toilet seat.

There is evidence of heavy fighting -- arrowheads, swords,

and the tombstone of a roman centurion.

But the most remarkable haul

is hundreds of mysterious chunks of wood.

Sketched onto them is ink handwriting.

It's the largest find of roman manuscripts in western europe.

They record life on the frontier before hadrian's wall is built.

Can these tablets explain why the romans are so afraid

of the barbarians to their north.

Andrew handles the latest discovery with great care.

Each postcard sized tablet is barely 1/16 of an inch thick.

One gives a unique insight into roman relations

with the barbarians of the north.

Andrew: This is an intelligence report

talking about british cavalry,

and basically saying how irritating they are there.

They have many horses,

but they have to basically get off their horses

to throw their spears -- they're not very, very effective.

Narrator: It's written around a 100 a.D.,

20 years before the wall is built.

The tablet reveals the fierce northern barbarians

wage a guerrilla war against rome.

Birley: They have to respond.

They've lost a lot of soldiers,

and one of the responses is to build hadrian's wall.

To shut down and lock down the frontier of roman britain.

Narrator: In the second century a.D.,

the roman army isn't just locking down

the border in britain...

The expanding empire creates

over 4,000 miles of new frontier,

which their legions are struggling to defend.

To stop aggressive tribes in africa and asia,

the romans build huge forts to house their armies.

To suppress barbarians in europe,

they build long palisades of wooden stakes and watchtowers.

♪

and after a deadly war in britain,

emperor hadrian orders a massive stone wall

running across the whole island.

♪

hadrian's wall is an epic engineering masterpiece.

Built to defend against northern barbarians.

But how does the roman army use this ancient wonder

to defeat their enemies to the north?

And does the empire equip the soldiers here

with its infamous deadly combat skills?

Discoveries near the wall hold a clue.

And later, in the heart of ancient rome,

how do engineers defy gravity to build the pantheon?

♪

♪

narrator: Hadrian's wall

is ancient rome's biggest megastructure.

The vast imposing edifice

reflects the empire's engineering skills

and massive military might,

a structure worthy of ancient wonder status.

It's built to defend against attacks

from northern barbarians.

♪

hadrian's wall marks the northern limit

of the empire's reach.

Having conquered across three continents,

the empire now needs this massive barrier

to defend its new land.

How does the roman army use the colossal construction

to take the fight to the enemy on their own turf

and maintain an empire of unprecedented longevity?

Evidence north of hadrian's wall offers a clue.

20 miles beyond the wall,

archaeologists find evidence of a ferocious battle at a site

known today as burnswark hill.

In roman times,

burnswark is one of the largest hill forts north of the wall.

An ancient center of tribal power,

its walls provide shelter for 2,000 barbarians.

Around the hill fort,

archaeologists unearth evidence of roman warfare --

dozens of carved red sandstone balls the size of grapefruits,

deadly missiles fired from roman catapults;

and hundreds of lead pellets the size of marbles.

What can these relics of ancient battles

reveal about how the romans use

this wonder of military technology

to defeat enemies north of the wall?

♪

archaeologist john reid uses pioneering drone technology

to hunt for clues to this 2,000 year old mystery.

Reid: Okay. Ready to roll.

Narrator: The high flying camera

reveals a huge network of ditches

at the base of burnswark hill.

They mark the edges of two roman camps

that surround the enemy's hilltop fort.

John thinks their close position is a clue

to the invading romans' plan of attack

and reveals what makes rome's wonders possible --

the unstoppable might of the roman military machine.

Reid: The romans know that the natives

did not have distance weapons.

For them, it's all hand-to-hand, face-to-face fighting.

Narrator: Many roman soldiers

in this strategic advance from the wall

are highly trained in the use of the slingshot.

John believes the position of their camps

is so roman slingers can bombard enemy troops.

He uses metal detectors to search this hill fort site

for evidence of an ancient aerial attack.

We have a lead slinged bullet. [ beeping ]

what this is effectively is an iron age slug.

It's a bullet.

This would have been shot from a sling

and aimed at some poor individual.

[ beeping ]

narrator: John finds over 700 slingshot bullets

at the site.

To get a better idea of how they're used in battle,

he works with andy nicholson, an expert in ancient warfare.

Andy and john investigate

the lethal range of a roman sling.

To do this, they use a replica weapon

and a ballistic gel,

which has the same resistance as human flesh.

The slingshot is a handheld rope pouch

that launches lead pellets at a deadly velocity.

♪

you're looking at a sling bullet

that's travelling at over 60 yards per second.

The impact damage is phenomenal.

And it not only breaks ribs,

it can cause internal rupturing and bleeding.

If one of these hits you in the head,

then that's the end of it.

Narrator: Andy's tests show the roman sling

is the handgun of the ancient world --

a killer weapon at over 100 yards.

The roman army is using maximum force

to advance its new invasion of the north.

John and andy plot the locations of their ancient finds

on a map of the site.

Their analysis allows them to piece together

how this pivotal battle unfolds

and how the romans destroy all their enemies

to expand the empire and construct more wonders.

♪

the romans build two camps on either side of burnswark.

From here, they deploy their catapult and slingshooters.

♪

they rain heavy fire down into the fort

to terrify and soften up the enemy.

Then 5,000 heavily armed ground troops rush from the camps

and storm the fort.

♪

any survivors trying to escape

die in a hail of roman slingshot fire.

Reid: Once the assault actually started,

it was complete extermination of every living being

on the summit of the hill --

men, women, and children.

♪

narrator: This annihilation

is designed to show all other tribes

what's in store for you if you dare stand up to the romans.

The roman troops blaze a destructive path

75 miles north of hadrian's wall.

The wall's huge military infrastructure is key

to supplying this new invasion with weapons, supplies,

and troops.

♪

today, this ancient wonders defensive strength

is no longer needed.

And 1,600 years after the empire's decline,

hadrian's wall still stands strong,

stretching from coast to coast.

It's a permanent reminder of the almighty strength

of rome's military machine.

But in the heart of modern rome,

one ancient wonder is surprisingly still in use.

How has the near 2,000-year-old pantheon

survived this long?

And what secrets does the buried roman city of pompeii conceal?

♪

narrator: The colosseum, hadrian's wall,

and the pont-du-gard aqueduct --

breathtaking wonders the romans build to last.

They surpass the icons of earlier civilizations.

♪

the fourth great wonder of ancient rome

is a remarkable temple dedicated to all the gods.

♪

the pantheon.

It stands strong after nearly two millennia

in the heart of the eternal city.

Impressively, it's still in use today.

Millions of people visit it each year.

Its longevity is testament

to ancient rome's colossal construction expertise.

The pantheon is built by rome's most prolific builder,

emperor hadrian, around 126 a.D.,

just after he orders construction of his mighty wall.

The pantheon takes its name from the greek "pantheos,"

meaning "all gods."

hadrian builds this remarkable wonder

to honor rome's greatest deities,

including king of the gods, the mighty jupiter,

his brother neptune, god of the sea,

with his iconic trident,

and mars, the famous god of war,

believed to be the protector of the roman state,

hadrian desires nothing but the best for his new temple.

But building a monument worthy of the gods

pushes roman engineering to its limit.

Hadrian designs an elaborate temple

with a 142-foot rotunda, a greek style colonnade,

and a mighty domed roof.

For the colonnade,

he ships in 16 granite columns from egypt,

each 39 feet long, weighing 60 tons.

For the rotunda, his engineers build a series of arches

and stack them on top of each other.

But building the 142-foot domed roof

will take some innovative engineering and design.

♪

the development of super strong concrete

proves the romans have a powerful command

of building techniques.

It allows this ancient wonder to stand the test of time

when so many have fallen.

But concrete is incredibly heavy,

and nothing less than a giant, unsupported dome

will do for hadrian's roof.

This poses a massive structural challenge.

So how do ancient engineers build this gravity-defying dome?

If they build the roof from solid concrete,

it could weigh 20,000 tons

and collapse under its own weight.

To make the concrete mix

they use in the top of the dome lighter,

they replace the heavy basalt-stone ingredient

with a much lighter pumice stone.

They make the dome thinner towards the apex

and cut decorative recesses into it

to shed even more weight.

And to stop the roof from spreading out and collapsing,

they install strong concrete rings around its base,

like steel hoops around a barrel.

And there's one final architectural solution.

At the center of the dome,

engineers cut a 27-foot-wide hole --

an oculus.

It reduces weight at the dome's weakest point,

but it also illuminates the temple

with a revolving circle of light.

The pantheon's breathtaking design

inspires architects for millennia --

the duomo in florence, Italy, a medieval masterpiece,

the united states capitol dome in washington

made from cast iron,

and a 21st century version,

the singapore national stadium

that boasts a world-beating

1,017-foot retractable dome roof.

However, today, the pantheon still remains

the largest unsupported concrete dome in the world.

This epic concrete wonder

is a temple still worthy of the gods.

It represents the pinnacle of roman technical innovation

and construction achievement.

♪

the romans build to last.

It's what defines their ancient wonders.

But one of rome's imperial masterpieces

has mysteriously disappeared from view --

emperor nero's magnificent golden palace.

Can traces of it be found buried beneath rome?

And what secrets does the frozen city of herculaneum hide?

♪

narrator: The pantheon is a masterpiece of roman engineering.

Its ingenious design ensures it still stands today.

But another extraordinary structure

rises decades before the pantheon's construction --

ancient rome's fifth great wonder,

the domus aurea,

emperor nero's golden palace.

Its legendary size makes it

one of the largest palace complexes in history.

Six of the seven original wonders of the ancient world

are built in deference to resurrection and the gods.

The hanging gardens of babylon

is the only ancient wonder built simply for pleasure.

And nero's golden palace is the same,

an opulent residence for the emperor alone to enjoy.

Today, only fragments of this vast residence remain,

but it's built after a devastating tragedy.

In the early hours of July 19, 64 a.D.,

a spark triggers a deadly chain reaction.

A devastating inferno breaks out

at rome's famous chariot racing track,

the circus maximus.

The fire spreads across the city,

destroying most of the capital.

After the flames die down,

emperor nero orders a vast new palace complex

to be built in the ashes.

It's called the domus aurea, or golden palace.

Archeologist valerie higgins

believes nero's reign begins well,

but it descends into cruelty and tyranny.

People had a lot of hope in nero,

but they started to change their opinion of him.

He murdered his mother.

And then he also started

these very self-indulgent

building projects.

Narrator: Ancient writers accuse the emperor

of burning down rome to build a gleaming new city.

He even has a name for it -- neropolis.

And at the heart of this gleaming city,

nero builds his golden palace.

♪

hidden beneath modern rome

lie the traces of this ancient mega palace.

Roman writers describe a building

with hundreds of rooms,

surrounded by lush gardens

and covered with gold, jewels, and mother-of-pearl.

Alongside, a private boating lake,

bigger than 10 olympic swimming pools.

And at the entrance, the crowning glory --

a giant bronze statue of the emperor nero himself

that towers 120 feet tall.

The domus aurea is a 200-acre residence

of unimaginable luxury.

Today, this wonder has all but disappeared.

♪

500 feet from the colosseum

lies the only surviving section of palace.

♪

archaeologist alessandro d'alessio

investigates the remains of this wonder.

♪

alessandro searches for what marks the domus aurea

as a true wonder.

Legend says the palace hides an astonishing secret

that sets it apart from other royal residences.

♪

a banqueting room

that supposedly rotates day and night.

For years, archaeologists think that this octagonal chamber

is the rotating room of legend.

Hidden windows give the impression

of the sun moving around it.

♪

♪

with this, historians believe

an actual revolving room is just a myth.

But a new discovery in this section of nero's palace

on the palatine hill

reveals that truth is often stranger than fiction.

Buried beneath this canopy

are the ruins of an incredible mechanism.

Two crumbling arches are all that remain

of a giant branching structure over 65 feet tall.

On the top, archaeologists discover

strange holes arranged in a ring.

♪

inside them is a soft clay,

possibly a lubricant,

a clue that they could've once held bronze ball bearings...

20 of them spinning in unison,

revolving the floor of the legendary dining hall.

♪

this incredible building sets the domus aurea apart

as a true wonder.

What does it take to build such a magnificent structure?

♪

today, the remains are buried deep behind these walls.

Archaeologist francoise villedieu

hunts for evidence of the ancient mechanism.

She heads down to the base of the walls

to investigate.

This room is one of the most sophisticated machines

in the ancient world,

but how do his engineers power it?

♪

utilizing one of rome's earlier wonders.

Does the emperor connect a nearby aqueduct

to his palace complex?

The remains of the aqueduct

lie close to nero's palace.

Nero can divert its water

to the base of his rotating dining room.

The water feeds a huge waterwheel

two stories high.

It turns night and day with the constant flow.

Connected to the wheel are a series of cogs and gears.

These transmit the force of the water up,

towards the rotating floor.

♪

the dining room perpetually rotates,

allowing banqueters panoramic views of the city

both day and night.

♪

this revolving masterpiece

is every bit as lavish

as the contemporary writers describe.

It exemplifies the sheer ingenuity

of roman mechanical engineering

and ensures nero's golden palace

becomes a true ancient wonder of rome.

The empire's wonders are built to last.

And have all withstood the test of time.

It's what sets them apart

from the lost wonders of the ancient world.

So what happens to the domus aurea?

And what turns pompeii,

a seemingly normal roman city,

into a frozen ancient wonder?

♪

narrator: The seven wonders of ancient rome

represent a new level

of astonishing engineering achievement.

They surpassed the original wonders of the ancient world.

They last longer, soar taller,

stretch further.

They completely transform how structures are built

and leave a lasting engineering legacy.

To this day.

But the fifth roman wonder, the domus aurea,

has all but disappeared.

Why?

Could the answer be found

in the origins of the golden palace itself?

Nero builds his magnificent domus

in the ashes of the great fire of rome.

Ancient writers accused the emperor

of deliberately starting the fire

to clear space for it.

But are the stories true?

And if so, can it explain the fate of the golden palace?

Archeologist antonio ferrandes

investigates the footprint of nero's ancient wonder.

He wants to work out if there is any truth

to the ancient accusations.

Antonio heads up rome's ancient palatine hill.

He uses modern satellite imagery

to reconstruct rome just before the fire.

Ancient writers claim

that nero wants all of this prime real estate.

Intriguingly, the footprint of the palace

matches vast swaths of the destroyed areas.

♪

the fire starts at the circus maximus.

It rages over six days in 64 a.D.

And destroys nearly 2/3 of the city.

It leaves a blank canvas

for nero's audacious rebuild.

On the charred hill where the roman elite once lived,

nero builds his golden wonder with over 300 rooms

and his revolving dining room.

And in the valley where once lay houses for the lower classes,

he erects a network of opulent palaces

and fills the gardens with wild animals.

♪

nero turns a bustling city center

into one of the largest private palaces in the world

right in the heart of rome.

♪

the evidence is circumstantial

but highly suspicious.

So, could the ancient authors be right?

Is the emperor capable of burning down rome

in order to build his own roman wonder?

♪

inside the last surviving remnants

of this remarkable golden palace,

archeologist alessandro d'alessio

pieces together more clues.

Alessandro believes the extravagant opulence

and sheer scale of the palace is the reason for its downfall.

But instead, the people send him a message.

Nero is overthrown.

The romans turn on this ancient wonder,

believing its creation is to blame for the fire

that devastates their city.

And after four years of construction,

romans ransacked nero's residence,

stripping off the precious jewels and gold leaf.

They drained the lake and buried the palace.

On top, they build rome's greatest wonder,

the colosseum,

a symbol of a city to be shared by all romans.

The ousted emperor flees the city

and eventually commits suicide.

♪

the controversial golden palace

is the only wonder of ancient rome

that has not fully survived.

It celebrates and commemorates just one man,

the emperor nero,

not the glory that is rome.

But it takes its place

on the list of rome's great wonders

due to the scale of its ambition

and the innovation of its technology.

Not all roman wonders are vast palaces or grand monuments.

Herculaneum and pompeii --

two ancient cities

that lie in the shadow of mount vesuvius,

transformed into spectacular wonders

when the mountain reveals its startling power.

Narrator: For centuries, the romans build a vast panoply

of awe-inspiring wonders.

Amazing amphitheaters and mega monuments

define an empire of engineering achievement

that outlasts the original

seven wonders of the ancient world

that come before.

The sixth roman wonder

is a wonder for a very different reason.

♪

herculaneum --

an entire roman city destroyed and preserved,

now locked in stasis.

Buried under 75 feet of debris,

a town frozen in time for nearly 2,000 years.

Roads crisscross the ghost town

flanked on each side by the scorched remains

of shops, bars, and homes.

But in its prime,

its streets are colorful and vibrant.

This town is home to over 4,000 people.

But just four miles to the east,

the sleeping volcano, vesuvius.

But exactly how does vesuvius preserve the town?

And what makes it a roman wonder?

♪

herculaneum is located south of rome

on the bay of naples.

Now, archeologists come here to uncover its secrets,

peeling back layers of debris to reveal its fate.

♪

in the remains of ancient boathouses,

they make a shocking discovery.

They unearth hundreds of skeletons huddled together.

♪

but there's one intriguing discovery that baffles experts.

♪

in a building on the corner of the main street,

a hidden room.

Inside, a stone plinth supports the remains of a wooden bed.

And in the center,

the skeleton of a man, buried where he sleeps.

♪

inside his exploded skull, a strange discovery --

unknown fragments that looked like glass.

What is this bizarre material?

And what can it tell us about the deadly event

that preserves this city,

transforming it into an ancient wonder?

♪

the man is locked for 2,000 years

under layers of debris.

Forensic archaeologist pier paolo petrone

is the first person to investigate his death.

He believes this body can reveal new clues

to what happens on the night he dies.

♪

ciao. Ciao.

Pier paolo takes the mysterious material

back to his lab

at the university of naples to investigate.

♪

♪

there's only one phenomenon

capable of delivering such devastation.

The infamous volcanic eruption of mount vesuvius

in 79 a.D.

It destroys herculaneum.

The force of the eruption

is powerful enough to incinerate flesh

and vitrify brains in an instant.

But with such a devastating force,

how has much of herculaneum been preserved?

♪

geologist guido giordano hunts for forensic evidence

to understand what preserves the city.

He investigates the volcanic rock

that covers the region.

This cliff is about 80 feet.

Now, this is enough to completely bury the old town.

Narrator: Guido believes the different layers of deposits

are like a volcanic fingerprint.

They reveal exactly what happens on the day of the eruption.

You can clearly see layering and changes in color.

The lower part is yellow. Then it turns into grey.

Looking closer to the texture and structure of the deposit,

we can work out it's actually made by several volcanic surges.

Narrator: For the first 12 hours of its eruption,

vesuvius throws gas and debris into the air

until it towers 21 miles into the stratosphere.

♪

northwesterly winds blow it eastwards.

And herculaneum to the west is initially spared.

♪

during the night, the ash tower collapses.

A surge of ash and hot gas barrels down the volcano,

blasting its way through herculaneum.

Five more surges bury the town's buildings

in thick layers of material,

preserving structures, objects, and victims almost intact.

This phenomenon is called pyroclastic flow.

Why doesn't it simply burn everything in its path?

Buongiorno. Ciao, ciao.

In his lab in rome,

guido sets up an experiment to investigate this mystery.

Giordano: We start with a piece of fresh wood

from the herculaneum area,

which is the same species of the carbon

that we find in the deposits.

Narrator: He puts the sample

inside a heating device called a calorimeter

to discover what happens to the exposed wood

from herculaneum during the eruption.

Giordano: Usually we think that

wood can burn with flame and oxygen in a fire.

Narrator: But a pyroclastic flow is a cloud of toxic gas.

There's no flame or oxygen, so objects can't burn.

♪

giordano: What we learned is that if we heat up

to a very high temperature with no oxygen,

this piece of wood, it carbonizes.

But it maintains its shape.

Narrator: In this fiercely hot oxygen-free environment,

the wooden objects and furniture turned to carbon.

A thick layer of ash then sets around the town.

It insulates everything in a protective layer.

Giordano: It is thanks to these unique set of circumstances

that we can learn so much about roman life

even after nearly 2,000 years.

Narrator: The catastrophic eruption of 79 a.D.

Devastates the area

and instantly kills the local population.

But at the same time,

vesuvius transforms herculaneum into a frozen ancient wonder.

Vesuvius is a killer,

but does its volcanic ash and debris

give life to another roman wonder -- pompeii?

A clue could lie in the very fabric

of the city's ancient buildings.

Narrator: Rome's greatest wonders are iconic monuments

that champion the glory of the mighty roman empire.

Pompeii -- our seventh ancient wonder

is world famous for a very different reason.

Also located near the bay of naples,

pompeii lies just a few miles along the coast

from neighboring herculaneum --

another roman city with its citizens

preserved beneath layers of volcanic ash,

suspended for millennia,

and now miraculously rediscovered.

♪

the eruption of mount vesuvius

buries buildings and boils brains.

The volcano destroys pompeii, killing all who remain.

Yet vesuvius once gives pompeii life.

♪

geologist guido giordano investigates the city.

He wants to discover how the people of pompeii

once benefit from the volcano.

Giordano: Everywhere you walk through this city,

you find evidence of volcanic material

being used in construction, and this is because volcanoes

produce a wide variety of rock types from hard

and heavy lavas to soft and light volcanic tuffs,

and in the bay of naples, those are everywhere.

Narrator: Pompeii's roman roads are laid with tuff lava stone

to withstand the heavy traffic of horse-drawn carts.

Decorative architectural features are sculpted

from softer volcanic tuff.

Do these materials help pompeii become a roman city of wonders?

♪

beneath a house in the south of the city

lies evidence of pompeii's original architecture --

stone foundations buried below the surface

that predate the surrounding buildings by hundreds of years.

They stretch back to the 6th century b.C.

Made from soft volcanic rock and packed into the ground

a mere 4 inches deep, these foundations are the roots

of the earliest structures in pompeii.

Could this rock explain why this city thrives?

♪

in 79 a.D., vesuvius has been dormant for hundreds of years,

but volcanic material from much older eruptions

forms the region's bedrock.

♪

building materials are fundamental

to understanding ancient civilizations.

This material is actually very soft, very easily workable,

but at the same time, it is strong,

and that's why pompeii is largely made

of blocks of tuff like this one.

Narrator: The volcano provides the raw material for early pompeians

to build their settlement,

but guido believes that when the romans conquer this region,

their ingenious use of tuff

helps them to supersize the city.

[ mysterious music plays ]

♪

he investigates a stone mine

deep beneath the nearby city of naples.

Here, ancient tuff can be found in its original state --

volcanic ash cemented into rock.

The citizens used carved blocks of tuff

to construct pompeii's grand public buildings,

but they also use it as a mortar.

When crushed, the rock turns back into loose ash.

One of the most revolutionary invention of ancient romans

was to mix this volcanic ash with quicklime

to produce a cement

that is actually able to dry even in wet environments.

Narrator: Like the discovery of super strong mortar at baiae,

the development of hydraulic cement

means romans not only build wondrous super-sized monuments

and structures,

but now they can also build underwater.

This invention allowed them to build concrete structures

and piers for their harbors,

and this is probably one of the key aspects

of the success of pompeii.

Narrator: This local wonder material

transforms pompeii's influence.

The advanced infrastructure of the bay of naples ports

enables pompeii to thrive.

Giordano: Pompeii had a prime location,

so no wonder it was flourishing in the 1st century.

Narrator: Mighty vesuvius is clearly key to pompeii's prosperity.

Pompeii is built thanks to the volcano,

thrives because of the volcano,

and is devastated but ultimately preserved by the volcano,

vesuvius is critical to transforming

this seemingly normal roman city

into the iconic wonder city we know today.

But the unique materials it provides

isn't the only marvel here.

♪

the wonder is what is preserved.

Astonishing discoveries at neighboring herculaneum

provide archeologists with unique insights

into ancient roman life.

Narrator: Rome's ancient wonders are incredible feats

of human achievement.

Iconic monuments that represent

astonishing engineering accomplishment.

But the last roman wonders,

the twin cities of pompeii and herculaneum,

are wonders for a different reason

their citizens are cruelly killed by vesuvius' eruption.

But the cities are miraculously preserved

by the volcano's ash.

♪

two cities frozen in time,

buried beneath layers of volcanic ash,

are the remarkable remains of life in ancient rome.

But what secrets does herculaneum conceal

that earns it a place among rome's greatest wonders?

♪

the city covers an area the size of 30 football fields,

but 3/4 of it remains buried.

Andrew wallace-hadrill is the director

of the herculaneum conservation project.

He investigates the mysteries

hidden within this preserved ancient city.

Herculaneum was destroyed in the same eruption as pompeii.

But unlike pompeii, the quality of preservation here

is quite exceptional.

Narrator: Herculaneum is a volcanic time capsule.

It is preserved in a flash,

burying clues that can now reveal

exactly how remarkable this city is.

Inside the buildings,

archaeologists discover thousands of objects.

One of the rarest things about herculaneum

is the survival of wooden furniture.

Here we've got a bed,

wonderful sort of chest of drawers,

and here's a very moving thing -- a cradle.

The baby was lying in the cradle when they found it.

♪

narrator: Today, archaeologists still excavate the town

from under millions of tons of volcanic ash.

In one corner, an enormous villa emerges.

What we see here is the cliff face of an enormous excavation,

and right down at the bottom of it is the villa.

♪

narrator: When the original excavation starts

at the huge villa,

workmen carve narrow tunnels

into the thick volcanic rock by hand.

After more than two years of digging,

they break through into a room

with strange black cylinders scattered on the floor

and on shelves.

Over 1,700 papyrus scrolls

baked black by the heat of the eruption.

This is the only intact library from the ancient world.

A monumental find.

What do these scrolls reveal

about herculaneum and roman life

that makes them so special?

♪

the tunnels excavated through the villa de papyri

are off-limits to most visitors.

Andrew has unique access to explore

this claustrophobic labyrinth.

These tunnels are still untouched

since herculaneum's rediscovery in the 1700s.

Hadrill: This is the tiny room in which the explorers

of the villa found hundreds of rolls of papyrus.

They looked like burnt lumps of coal.

Initially, they started chucking them away until they realized

"no, this is something much more precious.

There's writing on them."

narrator: What do the scrolls say?

And what can they reveal about their owner?

Hadrill: These papyrus scrolls are so blackened

that it's virtually impossible

to read the black ink against the black paper.

♪

narrator: Today, the fragile scrolls are stored here

at the national library in naples.

Papyrologist david blank works to decode

these mysterious ancient texts.

Blank: Reading the papyrus and reconstructing its text

and then making sense of it has been the biggest challenge

that I've had in my professional life.

♪

narrator: To decipher them,

david uses a groundbreaking technology created by nasa

called multispectral imaging.

It uses different wavelengths of infrared light

to separate the ink from the background.

Suddenly you could see whole lines of letters and text

that you could actually then reconstruct

into an intelligible piece of writing.

So in essence, we're using digital-age technology

to read something that was written 2,000 years ago.

And that's really pretty great.

Narrator: When david deciphers the fragments,

he discovers that most of the scrolls are written

by a greek philosopher.

It's a vital clue to the identity of the villa's owner.

Blank: This philosopher had a very important roman patron

who was piso.

And piso was also the father-in-law of julius caesar,

and so a person who can obviously afford

this extremely luxurious establishment.

Narrator: Julius caesar is one of the most famous romans in history.

Rome's all powerful dictator.

His father-in-law's villa

is one of the most magnificent ever found.

Andrew believes the discovery of piso's villa

reveals herculaneum as more than just a city.

It's one of the most important cities in the empire.

Hadrill: In its present state, you can only begin to imagine

the extraordinary size and beauty of this villa.

This is rich at a global level.

This is a guy who was father-in-law of julius caesar.

You don't get more important than that in roman society.

♪

narrator: Herculaneum is far wealthier and important

than its more famous neighbor pompeii --

two cities captured in time 2,000 years ago,

insights into roman life buried deep

now revealed to an astonished world.

Pompeii and herculaneum cannot match the colosseum for size,

the pantheon for technical genius,

or the domus aurea for opulence.

But their preservation through the power of vesuvius

makes them worthy roman wonders.

But could their deadly past offer a clue

to what may happen to rome's greatest wonders

in the future?

♪

narrator: Hadrian's wall in britain,

the pont-du-gard aqueduct in southern France,

and the pantheon in the heart of rome,

these ancient wonders exemplify the absolute best

of roman ingenuity and design.

Excavations at sites across the empire

continue to this day,

revealing stunning new evidence of this ancient civilization.

But they also give us a glimpse

of a possible devastating future.

One day, could all of rome's ancient wonders be buried again?

Volcanologist giuseppe mastrolorenzo

investigates mount vesuvius.

♪

he's trying to figure out whether the volcano

offers any warning of the fury it unleashes.

♪

but the volcano that towers above the bay of naples today

is a vastly different mountain

to the one that exists 2,000 years ago.

♪

vesuvius has erupted more than 30 times

since it consumes the twin cities

of herculaneum and pompeii.

Giuseppe and his colleagues at the vesuvius observatory

watch the mountain for signs of it stirring.

♪

it's not just vesuvius

that threatens the modern gulf of naples.

A ring of volcanoes surrounds the bay,

including europe's largest,

campi flegrei.

♪

if campi flegrei or vesuvius erupt again,

it will be a devastating catastrophe.

So despite the warning from history,

why, today, is the volcano blast zone

more populated than ever?

Volcanoes provide a wealth of benefits at all times

and occasionally severe hazards.

Giordano: The people of the east region

have learned to be resilient,

to cope with the volcanic hazard.

♪

narrator: Vesuvius and the region's other volcanoes

still pose a threat.

It's almost inevitable that one day,

they will erupt again.

When that happens, the ancient wonders of rome

are as likely to survive

as the buildings of modern day Italy.

Thanks to the empire's engineering excellence

and its ingenious use of super strong concrete,

rome's finest monuments

have endured the ultimate challenge --

to withstand the test of time.

After the great civilizations

that craft the seven wonders of the ancient world,

the roman empire surpasses the size, scope, and ambition

of the original marvels

and raises the bar

for the ultimate achievements of humanity.

By building smarter, stronger and longer,

the romans defeat their enemies and conquer new lands

to expand their empire

and build seven ancient wonders

that helped to define

the greatest civilization on earth,

ancient rome.

♪

♪

♪