Original subtitles

Italy. I just love this country.

The people, the places,

a history that reaches back over 2,500 years.

From the birth of the Roman Empire

through the glories of the Middle Ages

to the flowering of the Renaissance,

its achievements are just breathtaking.

But behind its glorious facades,

so much of that invention and creativity

still remains invisible.

Look at that!

I'm exploring three of my favourite Italian cities

to discover how their hidden treasures

played their part in the making of Italy and of Western civilisation.

I'll be working with historian Dr Michael Scott

to uncover the invisible layers of Italy's past,

in Venice, in Florence and in Naples.

You've got Nero murdering his mum.

Using the latest 3D scanning technology,

we'll reveal the secrets of how these cities made Italy

a powerhouse of the Western world.

We're starting our journey in Naples...

..where beauty and danger collide.

We'll be descending into time-travelling tunnels,

lost cities and ancient underworlds.

It's like we're walking through a giant's armpit!

We'll explore the living, ever-present threat

of Mount Vesuvius.

The brain down there boils, blows the skull apart.

But the volcano has also nurtured a thriving network of

Roman cities and seaside resorts.

Oh, look at this!

The scandalous pleasure palaces of their day.

It's all about sex.

It's a crime against love.

For the very first time,

our scanners will create a 3D model of the region

and I'll use virtual reality to get inside the scan.

Oh, I can see! It's completely 3D.

We're dusting all the sand away.

You can't miss this!

This is Italy as you have never seen it before.

Welcome to Italy's Invisible Cities.

My journey to reveal the secrets of Italy begins

on the way to the Bay of Naples, home to the brooding Mount Vesuvius.

Well, this is a way to start an Italian exploration, isn't it?

Right here in the dramatic landscape of the Amalfi coast.

Swooping around these fairly treacherous roads,

with a peloton of cyclists.

First time I've been here since our honeymoon.

Not our honeymoon, you understand. But the one with my wife.

Well, this is the country to come to.

And although we're going to be exploring

some of the most well-known cities in this landscape,

what we're going to be doing is getting under their skin

and revealing their hidden secrets.

We're going to be finding out how they've lived life on the edge

between beauty and danger.

I love you talking about beauty and danger

as we hurtle round these corners and I'm thinking,

"Oh, this is beauty and danger, isn't it?"

The motto of this place is carpe diem, seize the day.

Well, let's seize it with both hands, shall we?

We're going to be doing just that.

Wow!

THUNDER CRACKS AND BELL TOLLS

Look at this dramatic weather that's closing in on us here.

But that is as nothing compared to the drama of

the last 2,500 years of history that we're going to be uncovering

just over there in the Bay of Naples. I can't wait.

Dominated by Mount Vesuvius,

the bay is today home to a patchwork of towns and cities...

..the most famous of which is Naples itself.

One of the oldest cities in the world,

it's been occupied across 2,500 years by the Greeks, Romans,

Goths, Byzantines, Normans

and one of Europe's most powerful dynasties, the Bourbons.

And that's just before lunch.

Today, it's a sprawling metropolis of nearly four million people.

Noisy, frenetic and exuberant, it lives its life on the street.

But there's another, invisible side to Naples,

and Michael's taking me to a less glamorous suburb

to uncover one of its secrets from only 400 years ago.

If you want to really discover invisible Naples, well,

they're's only one place to go.

And that's... I'm guessing it's underground.

It's underground, yeah, absolutely.

A portal here to a taster of what is to come.

But this one is special because it's only just been discovered.

Oh, really?

'That discovery was made when a mysterious shaft was uncovered

'in this humble farmyard in 2014.'

So, when they were looking around, they immediately came to this.

And if you have a good look down, you start to get a sense of it.

Hold my feet, won't you?

Whoa! Oh, Lord!

That's most terrifying thing.

Oh! That's just miles down.

About 45 metres down, Xander.

How are we getting down there?

The good thing is, there is another way down.

Oh, you beauty!

We might still need some help to get down there.

'And that help comes in the form of the Naples Fire Brigade...'

THEY GREET EACH OTHER IN ITALIAN

Good morning. Alexander...

'..almost all of them.'

Ciao!

Sinkholes are swallowing up Naples with alarming regularity,

so the city has its own Department of the Underground,

and every time a new hole emerges, the call in the Fire Brigade.

I'm intrigued and... And not a little worried.

Why are there 20 of them?

Well, we wanted to be safe.

When the Fire Brigade first abseiled down the shaft to investigate,

they discovered another entrance at the bottom of this ravine.

Now, all we have to do is break into it again.

So, all of this path we've been walking down,

descended into jungle, slightly.

We're almost there.

Oh, whoa! OK.

And here we are!

HE LAUGHS

Look at that!

I mean, look at that. Look at that bridge across there.

This was only discovered, though, about two years ago.

This is a man-made quarry.

It's like some jaws of a shark or something, isn't it?

This place has been hacked out by hand by workers

over hundreds of years, beginning in the Renaissance.

What the miners of this quarry were after

was the volcanic rock here known as tufo, laid down 15,000 years ago.

It's some of the best quality building stone in Italy

and it's all thanks to the surrounding volcanoes.

This tufo came from this single eruption,

which means its consistency is so much better.

It's harder, tougher and, at the same time, easier to carve.

It's astounding, isn't it?

The scale of it. It's cathedral-like, isn't it?

It is.

In the 17th century, these galleries would have been filled with miners,

hoisting building stone to the surface through the shafts above.

Xander, look at this. A stairway to heaven.

All the way to the top.

Look at that. Probably about 50 metres above us right now.

You would not want to look down. No, you absolutely wouldn't.

Right. Do you want to have a go?

Hold that. Yes. Let's see how far we get up here.

'I'm not so sure how far I want to take this.'

Each of these are like little rock pools, isn't it?

I know, amazing, aren't they?

There aren't many stones that you would trust.

What an introduction this has been to Naples.

'Michael's meeting our scanning team

'to see how they're going to create the most comprehensive

'3D scans of Naples ever produced.

'This quarry is already pushing their technology to its limits.'

What's going to be the big challenge for you?

Well, it's just monumental in here.

So, we've got different techniques

to kind of get round some of those problems.

What we're using has only been released in the last kind of year.

'And in a first for our team, they'll even be scanning underwater

'to help create some of the most accurate 3D maps of Naples ever.'

We're going to be able to fly in through the bay, underwater,

up through the coast over Herculaneum,

deep underground and around Naples.

So it's all being tied together as one seamless map.

The scans are already working their magic.

The scale of the quarry is so breathtaking,

it really needs them to make sense of it.

As we break through the floor,

we can really see how enormous this complex is.

It's like an Alice in Wonderland warren for giant rabbits.

In the 17th century,

it provided the building blocks for modern Naples.

Only Paris was larger back then.

If this is a taster of what we can expect to see in Naples,

then this is going to be absolutely phenomenal.

To continue our quest, Michael has brought me to the heart of the city.

We aren't starting as you might expect with the Romans,

but with the dynasty that ruled here until 150 years ago,

the Bourbons.

Nice to get a little sniff underground there, Michael.

I see you've brought me back above ground.

Well, it was an amuse bouche, if you like. OK.

For what we're going to explore.

But I brought you here because this is Piazza del Plebiscito.

It's the largest public square in Naples.

And it was built by the monarchs

that ruled this place for over 700 years.

Michael is introducing me to one of those monarchs.

This guy is Ferdinand the Big Nose.

Your archetypal wannabe Roman Emperor,

but from the 18th, 19th centuries. I see.

One of the Bourbons who ruled much of Europe,

Ferdinand became the King of Naples

just as his cousins lost their heads in the French Revolution of 1793.

And old Big Nose himself looked to be heading in the same direction.

Naples was known for corruption...

..violence... Yeah. ..and prostitution.

I mean, you've heard the phrase, "See Naples and die."

Yes. So, that comes from when Naples was

the final stop on the grand tour, the English aristocracy,

here to see all the archaeological sites

and get syphilis from the prostitutes. Oh, I see, that's nice.

So, buy all the art and then... See Naples and die!

..take something extra. Something for the weekend.

Now, I'm sure what this guy wished he'd had

is what his successors went on to build,

which was a whole set of escape tunnels

underground from their Royal Palace in case things got too bad.

It does smack of a dynasty

that's taking a very long-term view of its position.

Well, the great thing about these tunnels is they connect into

a whole underground world that dates back to the very earliest

eras of Naples' history. So, this is not just a tunnel,

this is a time-travelling tunnel.

I'd been aware that Naples and Neapolitans,

an expression which generally was considered something rather fruity,

but I hadn't realised it was such a celebrated part of Naples' history.

"See Naples and die."

But these time tunnels, they sound very exciting indeed.

'Now all we have to do is find a way in.'

'Hmmm. Let's hope it's not there.'

We're looking for a vet's surgery.

It should be somewhere...here.

Is it a hole in the ground? We're looking for an entrance.

I'm hoping this door might be...

Ciao? C'e qualcuno?

Hello. Ciao! I am Gianluca. Welcome.

Alexander. Hi, hi, hi.

Come inside...

'Geologist Dr Gianluca Minin was the first to open up

'a huge section of the tunnels,

'blocked when they were used as a rubbish dump after World War II.'

What, you exposed all of this?

We needed six months, three people every day

to clean everything here. I suppose you couldn't guarantee

you weren't going to find something grisly. Yeah.

'Here we go. Down the rabbit hole.

'These steps descend 23 metres from the surface.

'It feels like a journey to the centre of the Earth.

'I'm not enormously fond of small spaces,

'so let's hope it doesn't get any tighter.'

Wow!

I mean, look at this! We are in the Bourbon tunnel now.

Ferdinand II was very worried.

And in 1853, decided to dig a tunnel

to connect the Royal Palace with the barracks outside,

very close to the sea.

And why is this so enormous if this is an escape tunnel?

Because we have a lot of layers of history here.

Not only the Bourbon time, but something before.

'What came before were the quarries used to mine the volcanic tufo

'that built Naples. All the Bourbon tunnellers had to do

'was join the ancient quarries together.

'Its uses didn't end there.

'After World War II, it was even a dump for abandoned vehicles.

'But it's also a time machine,

'taking us through Naples' 2,500-year history.

'Our scanning team are beginning the task of

'making sense of this labyrinth,

'whilst we go through another time portal

'to earlier in the 20th century.'

Hey guys, come with me,

I want to show you something from the World War II.

A bomb shelter.

'Naples was the most bombed Italian city in the Second World War.

'It's estimated that Allied raids killed more than 20,000 people.'

Look there.

We have found the beds.

XANDER GASPS The original.

And the toys for children.

Oh! Look.

Come with me.

You can read. "Allarme.

"26 April, '43."

And here,

"Noi vivi". "We are still alive."

Because it was better to stay here than outside under the bombing.

Nearly 200km of tunnels were cleared

and electricity cables laid

to cater for the hundreds of thousands of Neapolitans

forced to shelter from Allied bombing.

But life went on.

Alexander, look.

Green colour. Look at that!

It's oil floating on top.

Yeah. 70 years old.

I can open...

..and, please, smell.

HE GASPS

It's hair tonic, is it? Yeah.

Hasn't lost any of its potency, has it?

It was very important for the person who took with him.

Yeah, to bring it down.

Maybe he had a fancy lady down here.

Yes, many people fell in love underground.

Don't forget, we are a romantic people.

You're absolutely right.

It's quite tempting to think of this as

a rather sombre and poignant scene, but I don't really feel that.

I think the emphasis is on the "Noi vivi",

rather than the "Allarme".

Tremendous triumph of human spirit.

This labyrinth has given me a new perspective on Neapolitans.

Tough like their tufo.

Resourceful as well as romantic.

'Our final destination in the Bourbon tunnel complex

'moves us forward another 45 years

'and connects Naples' most ancient history

'with its most recent.'

So, welcome to the never-quite-finished metro line.

Started in 1990...

Oh, right, for...yes, Italia '90.

..and abandoned in 1994.

But why was it abandoned?

It ended up being such a mismanaged and corrupt project

that they just decided to...

Naples just hasn't changed at all, then.

Look at this! A ghost station.

We are below...

..where we started this morning.

No! What? Under the Piazza...

Piazza del Plebiscito is directly above.

Oh, it would have been lovely.

There it is. It's just the end of the line right there.

Yeah, just a solid wall.

But what I love about being down here is,

it's such a time-travelling experience.

We're in the 20th century here, but we've been in the 19th century.

We can go back all the way to the Romans.

When they were building one of the metro lines,

they cut across the Roman aqueduct for this area.

The Aqua Augusta.

It is one of the longest Roman aqueducts in the world,

right here, feeding the whole Bay of Naples.

And even before that, you can find the Greeks here because this was...

Neapolis. ..originally, a Greek colony of the fifth century BC.

So, this really does have 2,500 years of history

right here underground in these tunnels.

All crisscrossing right underneath Naples.

It's fascinating inside the tunnels,

but I'm keen to make sense of it all.

Matt from our scanning team has put together

the first scans of our 3-D model of the bay. Good to see you.

Are you well?

So excited about this, yes.

We are going to start off at Piazza Plebiscito.

In all of its glory.

That is beautiful.

If you could reproduce that on a canvas, I'd buy that.

I think it's beautiful!

The real purpose for being here is to take you

to this little alleyway over the side.

This was our little vet's shop.

Yeah, I mean, there's a whole new world.

From this tiny little entrance here, suddenly you're in an enormous,

enormous series of spaces.

I mean, thousands and thousands of individual chambers

all connected together. Wow.

These individual chambers which would have been quarried out

for their raw material... Right.

They then become a cistern,

and aquifer storing water for the properties above.

And then we have these much straighter tunnels

connecting them together. And that's the Bourbons coming in

and joining all of these ad hoc spaces together

into a complete network. You know, there's areas here

where there can't be anything holding the city up.

It's just the most baffling thing to discover.

You've got to do this sort of mad portal

into a whole splat of history.

And the maddest splat for me was the modern Metro,

destroying the ancient Roman aqueduct.

There it is, look. It looks like an exhaust pipe, doesn't it?

But that's our station.

Starting from here,

Matt has been uncovering the full extent

of the Roman aqueduct network.

The aqueducts span right the way from Plebiscito,

right out to the peripheries of the city

and they burst out above ground in the suburbs.

This is the Aqua Augusta.

Still very romantic somehow.

Just the idea of something tunnelling and then

suddenly appearing for a little short stretch above ground.

So there's just this incredibly extensive network

of underground spaces there.

Using their scans and researching old maps,

our team is building up a picture of the whole of Naples' underground.

Nearly 200km of aqueducts and their branches

inside the city alone.

Eight million cubic metres of rock from hundreds

of underground quarries

converted into household water cisterns.

All revealing how Naples' volcanic roots nurtured the city.

Surely, time for lunch?

But nowhere's safe from Vesuvius,

even when you're tucking into a Neapolitan food icon.

So, Xander, this isn't your first Naples pizza, though, I'm presuming.

Do you know? I think it is. Really? Mmm.

I mean, it's delicious.

But it's the tomato.

It's the tomato. Incredibly sweet.

And it's a special tomato.

Is it? The San Marzano plum tomato.

Grown in the volcanic soil which is abundant in this area.

Of course. Which is just full of minerals and full of...

So, they taste amazing.

So, the trade-off is you live under constant threat of eruption.

And, yes, you might all die in hot ash,

but for as long as you don't, you have centuries of great pizza.

You get great pizza and great tomato.

I mean, there's something about Naples, isn't there?

And probably good wine, too. Sorry to interrupt. And good wine.

This is from the area as well.

Growing in that fantastic volcanic soil.

But implicit in Naples is this sense of beauty and danger combined.

And Vesuvius is exactly that.

You know, there's the danger, but here's the beauty.

And for me, nothing epitomises beauty and danger

more than a scooter.

Oh, look at this! They're letting me back on a Vespa again.

Last time I rode one of these was in Rome. That was sort of fine.

I could do Rome.

Naples, I think, might be a slightly more tricky prospect.

But it'll be fine. What did your man say?

"Beauty and danger."

Here goes.

I'm off to explore the perils of living next to an active volcano.

I'm hurtling towards the town of Herculaneum.

It sits even closer to the ever-threatening Vesuvius.

And the volcano's exactly where Michael's heading,

to explore the source of Naples' wealth and its woes.

Roberto Adeo is guiding Michael to the business end of the volcano.

Slowly, slowly here.

So, you drive on the edge of the volcano.

From here you feel like Gods looking down on the world.

One more? Oh!

Here we are. And on your left, the Vesuvius Crater.

Oh, my God!

The crater rim towers nearly 1,300 metres over the suburbs below.

We are exactly on the edge of the crater that was formed

with the last eruption, 1944.

Before the eruption, it was almost full up to the edge.

So, in a couple of weeks, everything was removed from inside.

Eruptions of Vesuvius are rare,

but they are among the most violent in Europe.

So, what makes this a particularly explosive volcano?

Yeah, that's because... It's especially because

of this long period of rest.

Then it's like charging the energy for the next eruption,

so the chimney's plugged.

Magma's very deep inside, but then when it comes up,

after a long period of rest, normally it's with a big eruption.

When magma in the chamber below can't escape, the molten rock cools.

This causes bubbles to form and the magma to expand.

Roberto is going to demonstrate

just how explosive this ultimately can be.

I have Coca-Cola.

I have a drill.

I have Mentos...

The Coke represents the magma.

The mints, the effect of the bubbles

and the rapid change in pressure

once the magma breaches the surface.

One...

..Two...

Three. ..Three.

Whoohoo! HE LAUGHS

Amazing!

This area is such a hotbed of hidden volcanic activity,

it holds a secret.

Vesuvius isn't the biggest volcano in the Bay of Naples.

You got the different chambers.

Campi Flegrei, which is close to the surface.

So, there are two magma chambers underneath this area. Yeah.

Campi Flegrei means burning fields.

It's one of only 20 active supervolcanoes.

Its last major eruption 15,000 years ago laid down all that tufo.

Campi Flegrei is much more dangerous,

if possible, for the city of Naples.

First of all, because the city is exactly above the volcano.

And that also because in the past, this volcano had huge eruptions.

But it was another eruption from the much smaller Vesuvius in AD 79

that has defined our understanding

of the destructive power of volcanoes.

Vesuvius at that time was very, very quiet.

It had been quiet for 800 years.

So, they lost memories.

Nobody knew. So, when it erupted in 79 AD, it was a complete shock.

We all know what happened to Pompeii,

but the people closest to Vesuvius were the citizens of Herculaneum,

just 6km below.

No-one knows more about their fate than

Professor Andrew Wallace-Hadrill,

who's been studying the site for the last 30 years.

You have do imagine everything in dark, of course.

Because for 12 hours, the eruption's been happening.

Yes. And the odd thing is, nothing happens here.

Because the wind is blowing in the wrong direction for Herculaneum.

And we found no bodies.

No skeletons here in the main bit of the city.

Because they saw... They saw the warning and...

They ran. They weren't here.

That's for sure. And then, at about midnight,

this eruptive column collapses and you get pyroclastic surges.

You get great, billowing clouds of piping hot gas

and ash come cascading down the mountainside

and very, very rapidly cover up this city.

To a height that is way, way above

the height at which Pompeii is covered.

The depth is something like 20, even 30 metres, of solid rock.

So, if Herculaneum was buried under 30 metres of volcanic tufo,

how did it get to be discovered?

As the scan team starts to create a millimetre-accurate

3D map of ancient Herculaneum,

Michael is joining us to explore this remarkable story

in the town's best-kept secret.

Now, I've been promising Xander this is something special.

Yes. People really don't get much of an opportunity.

This is awesome. Down below here...

Yeah. ..is the ancient theatre.

Come down here and you see the real history of archaeology.

This is where it all starts.

300 years ago, treasure hunters were drawn here

when perfectly preserved Roman statues were discovered

during the digging of the town's wells.

They found loads of statues.

But it wasn't just statues they discovered.

Right down at the bottom, you can see, that is the theatre.

Wow. And that's it.

Right... You said there was a theatre here!

And you look right down onto the auditorium. And I can see it.

I can see the shape of the seats.

Come on, let's make our way down to Hades.

It's another 20 metres down through the rock

to reach the top of what was once an open-air theatre.

We are up in the top level of the theatre.

I'm guessing these are the restricted-view seats.

Well, the view was a little better

when there wasn't a million tonnes of rock in the way!

Certainly the cheap seats up here, for sure.

And here at last, this is where to sit.

And there's a story that there was a performance in full flow

when the eruption happened. That's right.

You spent the whole day in the theatre,

and if the eruption is at about midday,

it's reasonable there should be people already in the theatre.

This is a daylight, daylong festival

where the audience are supposed to be noisy.

The big people of town who have paid for the performance,

they're very anxious to get good reactions from the audience.

So, they'd be quite keen that come hell or high water,

or indeed an eruption,

everyone should pretty much stay in their seats, it'll be fine.

They want people packed in.

Bums on seats.

It's a sign of political power.

It's about the maddest thing in the world to try and understand

something as open as this theatre and yet we reach it

right at the bottom of this huge great tunnel.

30 metres of volcanic ash on top of us.

This place is so entombed, I'm wondering,

can we even get to the stage?

OK. Here are our steps.

You see how beautifully cut they are. Beautiful.

So, here we are. At last. Right down at the bottom.

We have found the stage.

And look at it, stretching right down there.

Look at that!

It's deep, deep, deep.

Look back here. Back it goes there.

So, if we come backstage here,

there's a wonderful spooky treat to show you.

Look at this.

THEY GASP

Out of the ceiling. No!

That's not... That's not one of our actors, is it?

No. That is the negative impression of a statue.

Somehow, the statue from right over there

has got blown by the pyroclastic surge

and formed an impression of the face.

The creases on his forehead.

I can walk on the stage,

but it's impossible to get a sense of its true scale.

To shine some light on this, we need our scans.

Another building block in our 3D model of the bay.

It helps reveal the outline of the stage itself in all its glory.

The tunnels excavated by the treasure hunters

help delineate the semi-circular shape of a 2,500-seat Roman theatre.

The scan also reveals where the theatre was set in the Roman town,

and that two thirds of Herculaneum is still entombed.

No bodies were found in the theatre,

so what happened to the people when Vesuvius erupted?

Andrew has brought me to a place at the edge of town

that recently provided the answer.

We're right down by the ancient sea where all this...

Oh, I see! ..green gunk is growing.

This was the sea. This was sea.

I see, and of course, that is just volcanic matter there.

So, everyone escaped, then. This is... They were thinking...

Well, come and meet them. Come and meet them.

And every single one of these arches is packed with skeletons.

We have this incredibly convincing image of a really ghastly death.

Do you see the way that their knees are contracted?

Yeah. What happens when you're hit by a thermal blast...

It's fatal. Everything contracts.

Yeah. And they're all found in what's sometimes called

the pugilist pose, as if they were fighting.

But they don't even know about it.

Sometimes, you find the skeleton with the top of the skull missing.

Because the heat is so intense that the brain down there boils...

MAKES POPPING SOUND ..blows the skull apart.

There's a detail. Wow.

I think, happily, they won't know too much about it

when their brains boil. Right, yes, right.

And it's very interesting they found not just skeletons in here,

but spread out onto the shore. And on the whole,

it's women and children right at the back

and young males out at the front.

Goodness me. It's all well and good to walk around ruins

and to talk about what happened, look up at Vesuvius and imagine.

It's a scene from hell, really.

400 people, one tenth of the population,

waiting on the shore for a rescue that never came.

Like Pompeii and several nearby Roman towns,

Herculaneum never recovered from the destruction of 79 AD.

Ten kilometres up the road, Naples was completely untouched.

A lucky break for the Romans,

because the city was one of the most important ports

in the whole of the Empire.

To find out what life was like in downtown Naples

just after the eruption, Michael's descending seven metres

below the surface of the modern city.

We've come to the Roman street

that is part of the central Roman forum and market,

and beneath this as well is the very origins of this city.

Its Greek origins with its Greek agora, its marketplace,

where you could buy food, chat politics

and catch up on what was going on.

And on top of it, the Romans have put their market,

with shops lining the route

where you could buy anything and everything.

And we're now getting to the fresh fish area.

These are the slanting tables that they'd have laid the fish out on,

the slant helping to wash off all the excess liquid.

And then on the floor,

you've got the water channels so they could clear it all away.

Our scanning reveals the influence of Roman Naples on the modern city.

The streets are planned on the same axis.

It also gives a sense of how big the ancient city might have been.

Its own partially-excavated theatre had a huge capacity of 5,000,

twice the size of Herculaneum's.

Roman Naples escaped unscathed the eruption of Vesuvius,

but 400 years later, after cataclysmic flooding,

it was buried in a mudslide.

Wherever you go in the city,

there's evidence that the trauma of these natural disasters

has been seared into its soul.

This is an extraordinary place. You've got these characters here.

The souls of the dead in Purgatory.

Here they are, burning away, waiting for the living to pray for them.

So, in the midst of all this life, death is right there.

A bit spooky!

Naples seems obsessed with religion and death.

With 448 churches, it's one of the most devout cities in the world.

It cares for its dead in some of the most exquisite cemeteries

and catacombs in Italy.

Those of the church of San Gaudioso are among the finest.

But strangest of them all is the cemetery of Fontanelle.

Until 1969, it was home to a cheery little group

called the Cult Of The Abandoned Souls.

Originally a tufo quarry - what else?

It became a repository for bodies from various epidemics.

In the 19th century, the bones were tidied

and locals adopted individual skeletons

and prayed for their souls in purgatory.

In return, they believed the dead would help Neapolitans

through their many disasters.

This is like walking down...

..the nave of some...

..nightmare abbey.

You could either think of this as the stuff of nightmares...

..or as something...

profoundly honest.

And this is the truth that none of this can get away from.

It's where we all end up.

Throughout their history, death, catastrophe,

calamity has been thrown down on these people.

They truly were living on the edge.

And I get a sense that this is a place where the membrane

between this world and the next...

..is very thin. I'm thinking of those people

sheltering from the bombing in World War II and that graffiti...

Do you remember? On the wall of the tunnel, "Noi vivi".

"We're still alive."

And there they were being helped by the dead.

The Bourbons, their tunnel.

A hand being held through the membrane of those two worlds,

in a way. There it is, this geological fault line

that, like it or lump it, means they are in two worlds.

And nowhere in the Bay of Naples represents that living fault line

better than the burning fields of the slumbering supervolcano

of Campi Flegrei.

This place gave rise to some of the most powerful stories

of the ancient worlds,

none more potent than the myth of the underworld.

The ancients believed that when they died,

their souls descended to Hades.

To get there, they crossed the underground River Styx,

the boundary between the worlds of the living and the dead.

According to the Roman poet Virgil,

"The gates of hell are open night and day.

"Smooth the descent and easy is the way."

Michael has brought me to the heart of the Campi Flegrei,

to the Roman town of Baia,

for my very own introduction to the underworld.

So, Virgil, the great Roman epic writer who wrote the Aeneid,

he lived here. And his character, Aeneas,

this is where he accesses the underworld.

And we're going to recreate one of those journeys for you today.

Of course we are! Yes.

I'm not sure what evil plan Michael's got in mind,

but Ivana Gidoni will be our guide.

And Ivana's a caving expert.

And is this the entrance to the underworld

that I've promised Xander?

Yes, it is.

Good. HE LAUGHS

This way for the underworld, Xand.

Extraordinary.

MICHAEL LAUGHS

It's a trench two metres and a half deep.

It's about, what? Half a metre wide?

60 centimetres, about. OK, fine. 60 centimetres. Fine!

And Xander, remind me, is it true you're a little claustrophobic?

I'm... I've been known to be claustrophobic, yes.

We can meet some animals also.

Some bats, scorpions.

Oh, good. Cave crickets.

Friendly Italian ones. Maybe some snakes.

Will they be released once we're in, or...? Rats and...

It'll be fine. Be fine.

'What's even more worrying is that

'Ivana comes with a whole team of speleologists.'

Am I allowed to ask yet what this is?

It's the entrance to the underworld.

That I'm getting!

As soon as some problem should arise, we should stop.

I am genuinely concerned. It's the fact there's going to be

someone right in front of me and someone right behind me.

So, if I suddenly have an "aaargh!" moment... We're there.

Yes, it's the being-there-ness that worries me!

Actually, what I really want is to be able to turn round and run out.

Oh, wow.

You'll be fine. It'll be absolutely fine.

Suddenly, it gets a little bit darker.

When this man-made tunnel was rediscovered in the 1960s,

the explorers thought they'd found the mythical entrance

leading to the River Styx - the threshold of hell.

The most glorious effect, these wet roots.

It's like we're walking through a giant's armpit

on a particularly hot day!

How you doing, Xander? I'm all right.

It's quite... It's quite exciting.

Wildlife quotient has gone up bit.

I can't remember what else he said we were going to expect.

Zebras, was it? I can't remember.

Now, Michael, we have reached a point

where the level of the floor starts to incline downwards

quite extremely. So, yeah, look out for that.

Whoa!

'The lower we go, the tighter the tunnel, the higher the temperature.'

Ah, right, I see. Right, the level of the ceiling, right, comes down.

Michael, how long do you think we've been going?

About quarter of an hour? Yeah.

Feels like we're about quarter of a mile into the earth, doesn't it?

Yeah. I haven't been laying my breadcrumbs, or whatever.

It was said to be easy to find your way into the underworld.

Yes. The real trick was finding your way back out again.

I'm... I'm guessing today we're not going to be recreating that, though.

MICHAEL LAUGHS

We've come to a junction here.

OK. It looks very much as though that tunnel goes underwater there.

So, please, God, can we not be going that way.

Let's go down first.

You brought your swimmers, right? XANDER LAUGHS NERVOUSLY

It should be pleasingly warm. I never quite know if he's joking.

Oh, I might go down on my arse, I think.

Yes.

Is that... Yes, that's water right there.

Look down. The river! The river is here.

There's every chance this could be the fabled River Styx.

Yeah, I mean, I have to say, we've been spinning you a bit of a yarn.

That's more of a... Don't... Don't ruin it!

..a tourist story than it is an archaeological reality.

No, no, no! I'm not being a killjoy,

but the real story is perhaps even more interesting.

Yes. Because this is definitely water heated by geothermal energy.

When this water was first tested, it was at 50, 60 degrees C.

So, the mystery is what is this man-made tunnel doing

if we're not here for the River Styx?

Well, to understand that,

it's probably best if we head back outside. Oh!

And I can show you what this might well have been doing here.

'I was out of that tunnel like a rat up a drainpipe.

'Once I'd recovered, Michael revealed what this was all about.'

That was hot enough to send hot air blasting up that tunnel.

And it diverts into three different mini tunnels

just before it comes out here,

coming to the underfloor area of this room.

I see! And those are the telltale signs right there of...

Yes. Underfloor heating.

So, where are we right here?

This is all that remains of a bath complex.

I see! This is what people came to Baia for.

And Baia was the largest set of thermal mineral hot springs

in the ancient world. Right here.

Right here.

So, Roman Baia was a spa resort taking full advantage of the

geothermal waters of the burning fields.

Our aqueduct, the Aqua Augusta,

even came through here to help quench its thirst.

We're off to see one of Baia's wonders,

fed by the aqueduct's waters.

VOICE ECHOING: Oh, look at this!

Listen to this!

Welcome to the Temple Of Echoes.

It's like a sort of mini Pantheon, isn't it?

The dome is half the size of the Pantheon in Rome,

but until the Pantheon was built in its second century AD version,

this was the biggest dome around.

But it's actually a swimming pool.

SPLASH ECHOES

Oh, look at that!

Oh, it's beautiful!

And how many Romans do you think sort of laid back

after a decent two-amphora lunch?

Recovering from the night before.

Saying, "Whoa, throw another stone!"

Baia was so popular as a spa resort

that the great and the good from emperors to ordinary citizens

flocked here in search of a cure.

But Romans being Romans, that wasn't all they came for.

On the one hand, you've got the Roman writers saying

that this place is a beautiful gift of nature.

Yeah. But on the other hand,

it's a place in which the Romans can really let their hair down.

You hear Roman love writers sort of pleading with their girlfriends

not to come to Baia because,

you know, the place is a crime against love.

It's just about sex here.

This was, "Come, fill your boots, we won't talk about it any further."

And there's one thing I'm wondering about,

is where did they live when they were here?

Well, just like any posh seaside town today,

the most expensive villas are on the seafront.

So, I imagine they've been sort of built over?

No, they haven't been built over, but they are hidden from view.

Well, from us here, at least.

Because they're actually now under the water.

Even powerful Roman playboys couldn't hold back a supervolcano.

Its heaving underground belly

constantly filling and emptying with magma

causes the coastline to rise and fall.

I've survived the underworld. Now I'm heading underwater.

And our scanning team is joining Michael and me

for the most ambitious stage of their mission.

In another first, they'll be scanning beneath Baia's waves.

All I have to do is get my wet suit on.

These are backward-facing wet suits, right?

Yeah, yeah, yeah, yeah, yeah. Xander...

Have I got the wrong...?

Oh, no!

LAUGHTER Yeah, I'm afraid you're...

This is going to be special for both of us.

Even Michael has never seen the treasures we've been promised.

Quite cold, so I'm preparing myself mentally for that.

NASALLY: And I'm talking like this.

Come on in, Xander, the water's lovely.

Honest!

He's not kidding!

This is Baia's lost harbour,

where the notorious Caligula is supposed to have refuted a prophecy

that he would never be emperor until he rode on horseback

across the water of the bay.

So, he tethered 4,000 ships together from this harbour wall

and trotted across.

No mistaking those columns, is there?

This area's called the Portus Iulius.

But it's the mole, the harbour walls that were sunk.

I was going to say, this is a functional building, isn't it?

Yeah, to create safe space. These are not your posh villas here.

No. No. Originally for the Roman military fleet. Yeah.

Now, I want to experience the posh villas

where I've been told the dining rooms contained sea-water pools

on which exotic dishes floated.

That may not be quite as easy as I thought.

As these watery gems have sunk even deeper beneath the waves,

we'll need to scuba-dive.

But only one of us is a diver.

Well, Michael's just gone overboard.

I mean, he's got... He's got the easy job here.

I, meanwhile, have got to sit here and man the comms.

Mikey Michael, this is Xander, are you receiving me?

Maybe that was something being plugged in.

'Can you hear me, topside? Over.'

Yes, I can.

Over. Loud and clear.

'Xander...this is absolutely incredible down here.

'I could do with a little champagne, I think, at this moment in time.'

Tell me what you can see, over.

'So, we're in one of the rooms

'of one of those posh, fancy villa owners.

'And I am currently in the process of uncovering

'this gentleman's mosaic floor.

'I don't know if his guests were impressed 2,000 years ago,

'but I'm certainly impressed today.'

Oh, Michael, that sounds incredible.

I'm just wondering how quickly I can learn to scuba dive,

so I can come down and join you.

MICHAEL LAUGHS 'You would absolutely love it.'

Michael, we've got a snorkel here.

I might pop that on. I can see it with a snorkel, surely?

'Absolutely. You can't miss this.'

'I also wish I knew what had happened in this...'

I feel like a war child listening to Churchill on the radio.

I just want... I want to get in there.

'Wow.

'If only this mosaic could talk.

'I'm sure it would have some fantastic stories

'and secrets to tell us all.'

Michael's description doesn't disappoint.

I can just imagine this as one of those villas

with sea-water pools and floating dishes.

But some Roman god with a sense of humour has taken it a step further

and inundated the whole villa with sea water.

It's like the tiled floor of some oligarch's gym, I should think.

Very beautiful.

And there's so much more.

Roads running along the seafront...

..countless amphorae and even a villa with its statues.

They're now faithful replicas,

so that enthusiasts can still share the magic of this lost world.

'I absolutely love it down here.

'This is the first time that I've been able

'to see this underwater world.

'Lost in time, wrapped in silence,

'as the sea levels have risen and the Earth has fallen.'

What a great place to experience.

The scanning team has almost completed its underwater mission.

What an experience. Extraordinary! Extraordinary,

then you come up and look at this bay anew and you think, well,

what must this have been like?

'We are better placed than ever before to find out.

'In another first for our scanning team,

'they're bringing it back to life as virtual reality.'

I'm going to show you Baia like you've never seen it before.

OK, shall I get in there?

Oh!

Oh, wonderful, I can see. It's completely 3D.

I see where we are. Look at this!

You see the little traces of algae and fish life around you.

I do! Look... Oh, and I can breathe!

Yeah, handy, isn't it? HE INHALES DEEPLY

It's fantastic. I feel like I'm snorkelling, slightly.

HE GASPS

So this is what Michael was talking about.

Look at that!

Incredible. I'm so dry! Yeah.

I think I'm going down for a little crawl on the floor,

just to have a closer look at it.

I feel like I've been dusting all the sand away.

Almost every tile.

Time to come up for air

and explore what the team has done with above-ground Baia.

Blimey, there it is.

There's Baia. It's like we've got a sort of tabletop train set.

Yeah. Or the best doll's house in the world. It's amazing!

Look at that! I mean, it...

The extraordinary thing is we never got a chance to see

how beautifully landscaped it is.

It's the weirdest thing in the world.

What about that! Amazing!

It helps build up an astonishing picture

of what Baia was like two millennia ago

before half of it was dragged underwater by the volcanic activity

that gave it life and then snuffed it out.

With our 3D model almost complete,

Michael has a plan to piece together all the strands of our story.

So he's taking me to nearby Miseno,

the port that succeeded Baia as the headquarters of the Roman fleet.

Thousands of sailors,

but also all the support staff were all suddenly based out of here.

It would have put enormous strain on the natural resources. Yeah.

And so they came up with a solution to be able to

at least give them water to drink.

This is just the most extraordinarily magnificent place.

Absolutely colossal.

So this is the largest ever Roman cistern,

built to hold the water that would be necessary

to supply such a large number of people.

And where did all that water come from?

I'm guessing this is the Aqua...

The Aqua Augusta, that we saw back in Naples. There we are.

The Aqua Augusta, that runs for 100km,

connects all the places we visited.

It's the thread that draws our 3D model together.

It shows how Baia really was two millennia ago.

It reveals Naples' hidden underworld

that helped it grow into one of the world's greatest cities.

And it shows the Roman towns that thrived in Vesuvius' fertile soils

before they were destroyed by it.

They've been so flabbergasting, the things we've seen.

I think the most beautiful thing was looking at the mosaic.

As you were sort of sweeping that away, that must have felt wonderful.

That was a magic experience. Something I will never forget.

And I think Naples is one of the places in the world

where you can really get a sense of people building on

the foundations of civilisations that came before them.

The layers of time.

Below ground, below the water and above ground, as well.

It's extraordinary and, you know, you look up here,

there's Vesuvius over there, and people have lived

in full knowledge of the shadow they might be under at any moment.

But, you know, they'll take that

for the joy of living in this beautiful place.

It's like a city that's entire history has been lived

as if during wartime. On the edge. Do you know what I mean?

Carpe Diem, as you said. We've just got to...

We've got to live! Intoxicating, heady,

but perhaps one to not stay in too long.

I think that's probably right. Yes.

I think... See Naples... See Naples and go home!

Next time, Venice.

Italy's amphibious city.

The smell of power reeking.

Welcome to the highlight of Black Death.

Right, we're off.

The city was devoted to erotic pleasure.

Weyyy, ohhh!

If you'd like to explore Naples in 3D yourself, go to...

..and follow the link.