Original subtitles

Narrator: the pantheon,

Ancient rome's best Preserved monument,

An engineering wonder

Unrivaled in its scale And pioneering construction.

Many scholars think it's

The most extraordinary Building ever built.

Narrator: buried inside This mighty edifice

Is an ancient mystery.

This tunnel is part of

A very extensive network That runs for kilometers.

Narrator: now, new evidence Beneath the streets of rome

Reveals clues.

The travertine slabs Are a window into

What this area May have looked like.

Narrator: how do the ancient Engineers build

Its impossible dome, with A gaping hole in the center?

And can pioneering 3-d scanning

Reveal who builds This ancient wonder?

We can see the fingerprints

Of this emperor In the pantheon.

Narrator: To unlock the mysteries of

Ancient rome's greatest Mega structure,

We unearth its foundations.

We digitally deconstruct Its mighty dome roof

And piece together clues At its feet

To decode the greatest secrets Of this

Incredible monument And the city around it.

♪♪

Rome, the capital of One of the greatest empires

In history.

Its ancient roots are Evident throughout the city.

Every structure Is a vital clue

To the mysterious world of The romans.

Right at the heart Of the city stands

The best preserved roman Monument in the world,

The pantheon.

Surviving for 2,000 years,

It's a miracle of engineering.

The pantheon is An iconic roman building.

In fact, it's one of The most famous in the world.

Many scholars think it's

The most extraordinary Building ever built,

And it's even more impressive When you think that it was

Designed and built 2,000 years ago

Without any of The advantages of modern

Technology that we have today.

Narrator: today, This extraordinary monument

Captivates millions of people Who come to visit each year.

16 towering columns Flank the entrance,

Topped with marble capitals.

Each one is carved from A single piece of granite.

Inside, the exquisitely Decorated circular

Interior is designed To impress,

And its 20-foot-thick walls

Are built to stand For millennia.

The roof is the largest dome Of its kind,

Over 140 feet wide, with A 30-foot hole in the middle.

Despite its venerable age,

To this day, the monument's True purpose is a mystery.

Valerie higgins Spends her life

Decoding the mysteries Of ancient rome,

And none are more enigmatic Than the pantheon.

The name pantheon implies that, At some point in the history of

This building,

It was a temple dedicated To all the gods,

Most particularly, The 12 olympian gods

Who were The most prestigious.

Narrator: the word pantheon Means "Temple of all the gods,"

But the pantheon's design

Is far from that of A typical temple.

When you look At it from this angle,

It just looks like A typical temple, a huge,

Enormous temple.

Behind it is This massive circular

Drum that we call the rotunda,

And you think, "That shouldn't Be on the back of a temple."

Narrator: most roman temples Are rectangular.

Instead, the pantheon's Combination of an angular front

And a curved rotunda at The back is completely unique.

Higgins: This isn't any temple.

This is something That's extraordinary.

Narrator: The pantheon's true purpose

Has puzzled Archaeologists for centuries,

But now, intriguing new clues Have appeared around

This monument that could help Crack the mystery.

Just a few months ago, A water pipe burst.

It created a sinkhole.

The cobblestones And the earth caved in.

What they revealed

Were paving stones that were Connected to the pantheon.

Narrator: the sinkhole Unearths a time capsule.

Just a few feet beneath The modern piazza

Are travertine paving slabs From an ancient roman square.

Following these puzzle pieces To the pantheon,

Archaeologists make An incredible discovery...

A marble staircase Leading up to a platform

And the remains of columns That are as old

As the paving slabs.

Can these buried stones Help reveal

The true purpose Of the pantheon?

♪♪

Paolo carafa investigates The mysterious

Remains of This older building.

The pantheon we see today Is the last chapter

Of a long history.

Our work has been To reconstruct

Such a long history.

Narrator: paolo and his team Create a comprehensive map

Of all the archaeological Discoveries beneath

The pantheon.

All these clues placed on A much more accurate map,

Reveal a structure exactly Similar to the pantheon

We see today.

The bulk of the structures Were part of

The original pantheon.

Narrator: the existence of An older, original pantheon

Underneath the pantheon We see today

Is an astonishing discovery.

Paolo's research reveals

The original pantheon Is built around 27 b.C.

His work leads to the man Who built it.

According to The literary sources,

The original pantheon is Created by the first emperor of

The roman empire, augustus.

Narrator: why does augustus Build this first pantheon?

Valerie believes she can find Clues in the surrounding city.

So here we are In the heart of rome.

It's full of buildings, It's full of people.

But it isn't in the least bit

As it would have been at The time of the first pantheon.

Narrator: to investigate The ancient area,

Valerie compares today's map Of rome with a map of the city

2,000 years ago.

We can see the pantheon here.

At the time of augustus, You wouldn't have seen

Anything in this area except The mausoleum of augustus.

Narrator: valerie suspects There is a connection

Between these two monuments,

And that augustus's mausoleum Is a clue to the purpose

Of his original pantheon.

Valerie has obtained Rare permission to

Launch a drone-mounted camera Above rome.

She wants to investigate The layout

Of the two monuments From the air.

If we take a drone to go up And to fly over the top,

We can have a look at how These structures

Relate to each other.

Narrator: valerie searches For the mausoleum.

From the site of The original pantheon,

The drone flies north over The rooftops of rome.

♪♪

Valerie locates Augustus's mausoleum

Half a mile North of the pantheon.

Its huge circular structure Makes it easily

Identifiable even From 200 feet in the air.

The eye in the sky reveals

The two giant circular Monuments are perfectly aligned.

Higgins: the pantheon And the mausoleum of augustus

Appear to be Facing each other,

And they are linked Along a visual axis.

Narrator: what more can The connection reveal?

Valerie heads to the mausoleum

Of augustus to investigate.

It is one of the largest tombs In the world.

This mausoleum tells us Quite a lot about augustus.

He's founding A big imperial rome.

This monument was built to be

A permanent memorial to him And his achievements.

Narrator: valerie believes The mausoleum and the pantheon

Are connected as part of An imperial design.

Having a pantheon facing The mausoleum that

He and the rest of his family

Are going to be buried in Indicate that they have

A very special status.

He is laying the foundations

For acceptance of a new form

Of government, of an emperor.

Narrator: the mausoleum's Perfect alignment

With the pantheon reveals

The original pantheon's True purpose.

Both buildings are Tributes to augustus,

Where he can be worshiped And venerated forever.

So why do the ruins of His original pantheon

Lie beneath The building we see today?

♪♪

In 80 a.D., Fire breaks out in rome.

It burns for three days,

Devastating the area Around the pantheon.

The fire spreads From building to building,

Engulfing The original pantheon,

Causing it to collapse.

The romans restore The pantheon

To its former glory,

But in 110 a.D.,

Lightning strikes And destroys it.

The rubble is cleared, and The present pantheon is built.

The original pantheon is Buried, but not forgotten.

The new version Stands boldly in its place.

But who builds This new pantheon?

Narrator: the pantheon, Built on top of an older

Temple to honor the first Emperor of rome, augustus.

But who builds the new Pantheon we see today?

Valerie higgins Believes that clues in

The structure will reveal The creator of this masterpiece.

Higgins: one of the first things That people notice is

The inscription across the top,

And that's in latin.

It tells us That marcus agrippa

Made this building When he was consul

For the third time.

Agrippa was the right-hand man Of the emperor augustus,

And we know That he was responsible

For the original pantheon On this site.

Narrator: rich romans often Inscribe their names

On the civic buildings They commission.

But something here Doesn't add up.

The pantheon We see today is built

More than 150 years after The original structure.

By that time, augustus And agrippa are long dead.

Hidden in the walls Of the pantheon

Are clues to the identity Of its designer.

Tile-shaped bricks

Carry the stamp Of the manufacturer

And the names of the highest Elected officials at the time.

Some bricks In the rotunda date

To the reign of emperor trajan.

But others date to the time Of the emperor hadrian.

So who, if it's not agrippa,

Is really the builder of The pantheon we see today?

Emperor trajan rules 84 years After augustus's death,

But only a small number of

The pantheon's bricks date To his reign.

Instead, the majority of The bricks date to

Emperor hadrian,

Trajan's successor who rules 100 years after augustus.

To investigate if hadrian

Is the builder Of the pantheon,

Paolo carafa explores One of hadrian's most

Famous creations,

Hadrian's personal villa.

It lies around 20 miles East of rome in tivoli

And is the largest villa In the roman empire.

Hadrian Loved architecture.

He trained himself As an architect.

He had been involved in The creation of this villa.

Narrator: but his construction Projects reveal

A much bigger ambition And pioneering ideas.

Carafa: hadrian had the great Vision of how architecture

Would strengthen And support his power.

He enabled the architect To push the innovation forward

To create a larger And more complex building

Than ever before.

Narrator: here At his villa, hadrian

Experiments with His innovative designs.

It covers more than 300 acres

With almost 1,000 rooms, Including banqueting halls,

Indoor and outdoor Swimming pools, and even

Underground parking For his chariots.

Carafa: the villa was The largest private residence

Ever built in the roman empire.

It was twice as large as The whole city of pompeii.

The dimension And the lavishness are a clear

Indication of the immense Power of the roman emperor.

Narrator: does this villa Conceal evidence that reveals

Hadrian builds the pantheon?

To search for clues,

Paolo heads To the maritime theater,

Hadrian's private retreat Within the grounds.

The size of The theater is what

Intrigues paolo and fellow Archaeologist fabio cavallero.

They use a state-of-the-art Laser scanner

To survey the site.

Narrator: fabio gets ready To start the scan.

These high precision digital Images allow paolo and fabio

To compare the floor plan

Of the pantheon to that of The maritime theater.

What they discover Is astonishing.

Carafa: the maritime theater Has the same

Diameter of the interior Of the pantheon.

Narrator: this could be Evidence that hadrian

Is the designer of Both buildings.

To delve deeper, The team scans

The entire villa, Looking for more similarities.

Our survey creates Point clouds to

Map every single corner Of the villa.

Narrator: the survey pinpoints A structure with a semi-dome,

The canopus, that has even Closer similarities

With the pantheon.

Carafa: here we have An excellent example of

Hadrian's experiments With domes and semi-domes.

Narrator: these similarities are Conclusive evidence

That hadrian builds The new pantheon.

We can see the fingerprints Of this emperor

In the pantheon And in hadrian's villa.

Narrator: but if hadrian Builds the pantheon,

Why is augustus's friend

Agrippa's name on the front Of the building?

Valerie thinks a clue May lie in what

Romans think of hadrian and His great predecessor.

Higgins: hadrian was quite Disliked in his own time.

By the second century, People are thinking that

Nobody since augustus had Really matched up to him.

Narrator: the romans see Augustus as the epitome

Of a successful leader.

In 27 b.C., he becomes the very First emperor of rome.

Augustus rapidly Expands the empire,

Conquering egypt, Central europe,

And northern spain.

But when hadrian Becomes emperor,

He halts the rapid expansion.

He believes that the empire Must protect its borders.

He builds monumental Defenses, like

The famous hadrian's wall, Across britain.

But this conservative approach Doesn't make him popular.

Higgins: to win the romans over, Hadrian devises a plan.

Hadrian thought That he could raise his status

With the roman people

To portray himself As a second augustus.

Narrator: so he decides To imprint on the facade

Of the pantheon the name of

Augustus's great friend, Agrippa.

Higgins: hadrian tries to Emulate augustus by rebuilding

The pantheon and making An obvious reference

To augustus.

Narrator: hadrian is the proud Builder of the pantheon

We see today,

But he's not finished with his Mission to emulate augustus.

He makes one final Monumental statement.

In 123 a.D.,

15 years before his death,

Hadrian builds His own tomb,

Now called castel sant'angelo,

His mausoleum dominates The west bank of rome's

River tiber, So no one can miss it.

Hadrian's mausoleum, His lavish villa,

And the pantheon

All reflect his vision for Rome and his impressive empire.

Hadrian sets out to outbuild His predecessors.

His pantheon is bigger And better than the original.

But how does hadrian Ensure his pantheon

Won't burn down like Augustus's?

Narrator: the pantheon.

Built by the ingenious Emperor hadrian on

The foundations of augustus's Original structure.

But how does hadrian ensure That his pantheon

Is indestructible

And won't burn down

Like his predecessor's?

Hadrian's pantheon is still So perfectly preserved

After almost 2,000 years,

This area has been Hit by earthquakes

And struck by lightning And yet...

It's still here, intact.

This is a real miracle Of engineering.

Narrator: the outside Of the pantheon's walls

Is just bricks Covered in plaster.

Their real strength Lies within,

A rock-solid core of roman Concrete to support the roof.

But building decorative Niches and recesses

Into the walls Creates weak spots,

So roman engineers build brick Arches into the pantheon

To channel the weight of The roof into the thicker parts.

Is this clever combination of Brick and concrete

The secret to the survival of The pantheon?

Guido giordano is an expert

In ancient roman Building materials.

He's on a mission to discover The secret to the concrete's

Incredible strength.

The mortar is made Of this white-ish base

And lots of these floating Elements, very dark in color,

And it's this particular Component that makes

This concrete so stronger Than any other concrete.

Narrator: What is the secret component

Of this special concrete?

Guido investigates the rocks That surround rome for clues.

In the grounds of Tor marancia park

Guido finds a distinctive Rock formation,

The result of ancient Volcanic eruptions.

These volcanic explosive Eruptions were 10 times

Larger than the one That buried pompeii.

Narrator: Can rocks like this unlock

The secret of roman concrete?

Guido finds a mysterious Tunnel carved

Into the volcanic rock.

He instantly recognizes This structure.

This tunnel is part of a very

Extensive network that runs For kilometers underneath rome,

Exploiting the underground.

Narrator: it's inside tunnels Like these that

The romans discover the secret Ingredient for their concrete.

Giordano: this tunnel is An ancient roman quarry.

This is where the romans Excavated the volcanic

Material for the concrete Used to build the pantheon.

Narrator: the secret ingredient Of the roman concrete is

Volcanic ash.

This is loose, so very easy To be excavated,

But also hard enough to hold A tunnel that is made of a wide

Variety of particle sizes that

Go from very fine ash to much Larger volcanic [indistinct],

And it is This variety of particle

Sizes that provides A very strong interlocking.

Narrator: this material is A game-changer for the romans.

They learn to use Volcanic ash instead

Of traditional quartz sand To make their mortar.

Guido recreates The roman concrete mix

To test its properties.

He starts With the volcanic ash.

Then he mixes it With lime and water.

So this is roman concrete, This is

What was used To build the pantheon.

You can see how easy It is to work it.

It's very wet, And it doesn't hold anything.

But over time, The volcanic particles inside

Make a very special

Kind of minerals that are not Found in the classic,

Ordinary mortar.

Narrator: Now, to compare the mortar

Made with volcanic ash,

He repeats the process, mixing Lime with the traditional sand.

This mimics the concrete used

In the buildings Before the pantheon.

We put the mortar on top,

And then we put another stone...

And wait.

Narrator: two hours later, The two different mixtures

Have solidified

And are ready to be Put to the test.

We already see a strong Difference between these two.

Here, the mortar is still Very wet and ductile,

Whereas

In this one, you can see that It has already hardened.

This is the one made With the volcanic ash.

Narrator: the volcanic ash Concrete is the clear winner.

This material triggers A revolution in

Roman construction.

These will become The strongest link between

These two pieces of rocks

And the strongest mortar Ever invented.

Narrator: this new concrete has One last crucial benefit.

Giordano: roman concrete Is so strong, it resists

Even to high temperatures In case of fires.

Narrator: this material is The reason this city's

Most magnificent buildings Have survived for millennia.

Hadrian's engineers Create an indestructible

Pantheon that ensures He's remembered for eternity.

But how do they build The seemingly impossible roof,

The iconic dome?

Narrator: Right in the heart of rome,

The pantheon has the largest Dome of its kind in the world.

This hemispherical dome is The largest ever built

Until reinforced concrete

Is invented at the beginning Of the 20th century.

Towering 100 feet above The streets of rome,

It stretches 142 feet Across the pantheon.

The walls at the base Are 20 feet thick

And taper to just 5 feet At the apex,

And the concrete inside them Is cleverly adapted.

At the bottom,

It contains crushed bricks To make it strong,

And at the top,

It contains fragments Of pumice stone

To make it light.

On the inside, Cut-out recesses

Trim down the weight Even more.

But how do ancient roman

Engineers actually build This colossal dome

100 feet off the ground?

Tullia iori is an expert In roman construction.

Narrator: the enigma of The dome's construction inspires

The roman people to devise Their own theory.

Legend says that To build the dome,

Hadrian creates a huge mound Of earth

And hides gold coins inside.

He uses the mound of earth As an enormous mold,

Casting the pantheon's dome On top.

Then he invites The citizens of rome

To remove the earth Inside the pantheon

And keep all the coins They find.

Narrator: Tullia believes that instead,

The romans invent a new Construction technique

To build the dome.

Tullia uses cutting-edge 3-d printing

To investigate the dome's Mysterious construction.

She recreates a miniature Version of the structure.

Narrator: until the invention Of reinforced concrete,

Most domes are assembled On the ground and lifted

Into place.

But this colossal dome Is constructed

Exactly where we see it today.

How did the romans manage this Seemingly impossible feat?

Tullia thinks They have two options.

They could build An internal scaffolding from

The ground up to support The dome from beneath.

Or they could build One ring after another

And hope that each ring Will support the next one.

But even when complete, The risk isn't over.

The dome weighs A mighty 5,000 tons

And could collapse Under its own weight.

Tullia uses a clay model of the Dome to investigate the risk.

She pushes down on the model

To simulate the weight of The concrete.

Narrator: The pressure at the top

Creates tension at the bottom

That eventually cracks The lower edge.

How did the romans ensure

The dome doesn't collapse Under its own weight?

The key To the dome's survival

Lies in an ingenious Engineering trick.

To prevent the lower edge From cracking,

The romans secretly bury The bottom half of the dome

Inside the rotunda.

This way, the pressure is Contained by the walls

And external step rings,

Ensuring the full stability Of the structure.

Narrator: the romans use These techniques to create

A structure made to last For millennia.

Narrator: By building the pantheon,

Emperor hadrian changes The landscape of rome forever,

And he creates one of The city's most

Iconic buildings.

But why do Hadrian's engineers

Leave a gaping hole At the pinnacle?

What is its purpose?

The pantheon is An engineering marvel.

The unreinforced Concrete dome

At its top is The largest in history.

At the pinnacle of the dome

Is an unusual feature Called the oculus.

It's a 30-foot-wide hole That opens the pantheon to

The heavens But also the elements.

[ thunder crashes ]

To deal with rain,

The marble floor beneath Gently curves like a bowl.

It collects water And drains it

Through 22 cleverly concealed Drainage holes.

When the sun shines,

The oculus creates a beam of Heavenly light that moves

Through the pantheon.

Where does emperor hadrian get

The inspiration For this bold feature?

Narrator: Archaeologist paolo carafa

Examines another oculus In the ruins

Of hadrian's famous villa To investigate this mystery.

This miniature oculus, Just 3 feet wide,

Has a surprising purpose.

Carafa: These are the great bath.

This was the hottest room in The bath, like a steaming room,

And it was covered by a dome With an oculus in it

Exactly like the dome of The pantheon.

Narrator: today, half of This dome is missing,

But paolo's reconstruction Leads him to believe the oculus

Plays a critical Functional role

In this structure.

We can imagine people sitting On the benches all around this

Wall with the steam flowing Out of the hole in the dome.

Narrator: here, the function of The oculus is to let

The steam from the baths out Through the hole in the ceiling.

The oculus is a key feature Of roman baths for nearly

A century before

Hadrian creates his In his villa.

The temple of mercury bathing Hall in the nearby spa town

Of baiae, has one of

The largest oculi Of its time.

But in all roman baths, The dome and oculus

Are always part of a larger Complex of bathing pools.

The buildings never stand Alone, like the pantheon,

And no oculus has Ever spanned so wide.

The pantheon's supersized oculus Is twice as

Wide as that In the temple of mercury.

So what is its purpose?

Carafa: in the pantheon, The oculus is a void space

Created to sustain The whole dome.

Narrator: hadrian's engineers Use their oculus

To reduce the weight of The dome.

This makes the largest dome in

The world at that time A reality.

Then they use the effect The oculus creates

To give the pantheon An ethereal, heavenly aura.

But hadrian goes One step further.

His engineers expertly Design the orientation of

The oculus and the door To align with the sun

Each year on april 21st, Rome's birthday,

When he enters The pantheon,

Hadrian is bathed in Awe-inspiring light.

It makes him appear Almost divine.

The spectacle amazes The people inside.

No other building In the whole of

Ancient rome has ever created The same effect.

How does hadrian formulate Such a sophisticated design?

Carafa: Hadrian traveled a lot.

He travels All through the empire,

And he claimed he was the only Emperor to have seen every

Place in his empire.

Narrator: do hadrian's travels Across his empire also

Inspire the pantheon?

In his youth,

Hadrian is nicknamed Graeculus, meaning greekling,

Because he likes to immerse Himself in greek studies.

As emperor, he frequently Visits greece.

He admires the culture And architecture

And sponsors the construction Of grand temples there.

In return, the athenians Build him a grand arch,

Naming him as a co-founder Of their city.

Back in rome, he builds A lecture hall called

The athenaeum to promote The greek way of thinking

Among romans.

♪♪

Hadrian wants to make rome In some way the inheritor of

The culture of athens,

To leave it as his legacy.

Narrator: hadrian's greek legacy Is secretly

Embedded into the design Of the pantheon.

He uses scientific principles Developed by

The greeks to design The pantheon with

Perfect symmetry.

This faultless design gives it A sense of supreme harmony.

Hadrian creates a building Filled with greek features,

A record-breaking oculus, And made of

Indestructible materials.

But how is the pantheon used When hadrian no longer

Rules rome?

Narrator: The powerful emperor hadrian

Creates the pantheon To fulfill his vision

Of a world ruled by Greek harmony and beauty.

But what happens To the pantheon

After hadrian's death In 138 a.D.?

The magnificent building Is used as

An audience hall For more than four centuries,

But in 608 a.D.,

After the advance Of christianity,

Emperor phocas transforms The pantheon into a church.

Narrator: For 14 centuries,

To this day, the pantheon Remains a catholic church.

Throughout this time, It's been

A constant source Of inspiration.

Renaissance engineer filippo Brunelleschi spends 10 years in

Rome, studying the pantheon To unlock its secrets.

When he returns to florence,

He builds the dome of santa Maria del fiore cathedral.

The dome has A diameter of 147 feet.

Its dimensions exceed the Pantheon's immense clear span.

100 years later, Michelangelo draws inspiration

From the pantheon

For the iconic brick dome of St. Peter's basilica in rome.

But the influence of

The pantheon travels Much further than italy.

The rotunda at the university Of virginia is built in 1822.

It's designed by u.S. President Thomas jefferson,

Who is inspired By the pantheon.

It is the focal point Of the school.

Jefferson is an architecture Enthusiast, just like hadrian.

The jefferson memorial, Built in the 1940s,

Is a tribute to one of The founding fathers,

As well as To his architectural designs.

And right in the heart Of washington, d.C.,

The pantheon is forever Remembered in the rotunda of

The u.S. Capitol,

The ultimate symbol of Democratic government

In the world.

Higgins: The pantheon symbolizes

A type of architecture That has been used

Throughout the world To indicate

Public buildings that Carry great weight

And that are hugely important For the nation.

Narrator: today, The pantheon remains one of

The most famous symbols Of rome.

Hadrian's legacy is Long-lasting.

The pantheon continues to awe All that enter its doors.

But once a year, his oculus Finds a new purpose.

Narrator: from religious To public buildings,

This mighty structure has been A constant symbol

Of innovation.

Emperor hadrian uses his villa To trial ingenious

Engineering feats

And draws on buildings from Across his empire to create

The ultimate monument,

Built to last forever.

Higgins: this building Is the best preserved

Roman building that we have, And it shows us the genius,

The spirit, Of roman architecture.

Narrator: The pantheon is one of rome's

Most astonishing achievements,

An engineering marvel With a record-breaking roof,

Roman concrete at its heart,

And clues to its past hiding Beneath its foundations.

The iconic pantheon Still stands strong

At the heart of rome,

Connecting the past and Present of this eternal city.

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