All language subtitles for BBC.Italys.Sunken.City.1080p.HDTV.x265.AAC_Eng

The Roman settlement of Baiae

was the Las Vegas
of the Roman Empire -

a place where the rich
and powerful came to relax,

party and carry out
illicit affairs.

Lured by Baiae's volcanic hot
springs, the Romans built

opulent villas and baths
here on the Gulf of Naples.

Today, it is still famed
for its precious marbles,

mosaics and sculptures.

The ancient authors wrote a lot
about Baiae and described Baiae

as a little Rome -
as a place for the holiday,

a place grounded with
all the aristocracy,

but also with young people,
with people walking

on the beach, looking to
the sea, people drinking wine.

A fun atmosphere.

It sounds like a party town.

Exactly.

LAUGHTER.

But over several centuries
the city slowly sunk

beneath the sea.

Burning.

This area?

More dangerous than...there.

I wish you told me that
when we were over there.

Why are you telling me
that when we're here?

The underwater site
is a treasure trove of mosaics

and marbles dating
back 2,000 years.

But today they are at risk.

Now a team of archaeologists
and engineers are developing

some surprising new
technologies to protect

the underwater site
for future generations.

We know Baiae as
the underwater city.

Baiae is not an underwater
city, it is kilometres

of the ancient waterfront
that is now underwater

because of a sudden
change of the sea level.

You can see underwater
the remains of actual

the villas, also the remains
of marbles, streets, shops.

Is there anything else
like that in the world?

I don't think that you can find
other underwater archaeological

sites in the world like Baiae.

Baiae, on the Gulf of Naples,
is one of the most

extraordinary ancient
sites in Italy.

The Romans came here
for the same reasons we do -

the sparkling Mediterranean,
the balmy weather, the lush

vegetation and vineyards.

They were also drawn
to the area's thermal springs -

the result of course,
of the volcanic activity

beneath their feet.

As the Roman Republic lapsed
into Empire, Baiae's

reputation only grew.

In AD 39, Caligula built
a bridge made up of merchant

ships linked together and then
covered with earth from Baiae

to nearby Pozzuoli -
three miles long -

and rode over it in a chariot.

And in AD 59, Nero had
his mother, Agrippina,

murdered in her villa here.

The later Emperor Hadrian
would have a more peaceful end

to his life, dying of natural
causes in his Baiae palace

in AD 138.

University of Naples
"L'Orientale" archaeologist

Michele Stefanile
showed me around.

Baiae was a luxury resort
with incredible architectures

connected with the most eminent
men of the Late Republic

and the early Imperial times.

The ancient authors wrote a lot
about Baiae and they described

Baiae as a Rome -
as a place for the holiday,

a place crowded with
all the aristocracy,

but also the young people,
with people walking

on the beach and looking to
the sea, people drinking wine.

A fun atmosphere, it
sounds like a party town.

Exactly.

People like Seneca,
for example, decided

to have his villa not
in Baiae but on a hill

in that direction.

Just to stay a little
bit isolated for the...

It was too loud for him?

Exactly.

Too crazy for Seneca.

Exactly.

And when did this
whole area disappear?

We know that after the Late
Antiquity, this part

of the territory, of
the Phlegraean region

was abandoned.

So, how much to
the water level rise?

It depends on the part
of Baiae, but normally it's

somewhere between
four and six metres.

Wow.

It's a big change.

It's a big one.

Yes, a very big change.

That's why you can see
underwater, not only

the floors, but also walls.

It's one of the sites
in the world with this

concentration of mosaics
from the Roman times,

times, underwater.

So, you can ride on the water
and read a mystery five

centuries long or six
centuries long.

So, tell me what happened.

How did it get submerged?

The history of the change
of the sea level in this

territory is connected
with the volcanic activity.

Most of us have heard
of Mount Vesuvius, but it turns

out there's another
volcanic zone near Naples.

It's burning.

It's more dangerous
than...there.

I wish you told me that
when we were over there!

Why are you telling me
that when we're here?

This area - called Campi
Flegrei, or the Phlegraean

Fields - is still active.

It's also why Baiae
is now underwater.

The movement of magma
underground actually sank

the ancient city's
ground level.

Campi Flegrei is one of the 20
known supervolcanoes

on the planet, capable
of erupting with a volume

of thousands of times stronger
than an average volcano.

Vincenzo tells me that if it
were to blow at maximum

capacity today, it would
make the AD 79 eruption

of Mount Vesuvius -
that destroyed Pompeii -

look like a puppy's sneeze.

Carmine Minopoli is
a researcher at the National

Institute of Geophysics
and Volcanology.

He walked me through how
the monitoring system works,

but before he did, we spoke
in one of the stranger places

I've ever done an interview -
inside a building that had been

abandoned because of
the heat and gases caused

by the volcanic
vents beneath it.

All of that volcanic activity
remains a risk today.

But it's also what put Baiae
underwater 1,500 years ago.

The water has helped
preserve the artefacts,

but it can also damage them.

Barbara Davidde, director
of the unit of underwater

archaeology at Italy's High
Institute for Conservation

and Restoration, has been
working at Baiae since 1993.

So, 1,500 years these artefact
have been underwater.

What does the sea water do
to artefacts over such a long

period of time?

Archaeological remains
were protected underwater,

thanks to the sea.

But if they are on the seabed,
open, and so not covered

by the sand, they are attacked
by marine organisms.

We call bioerosion.

There are sponges and bacteria,
also bivalve animals,

organisms, so there is a big
variety of bioeroders.

Some statues that are recovered
from the sea are completely

destroyed or partially
destroyed or sometimes

that we found

that the neck, the head,
the hand, is lost.

And all the portion
of the statues that are covered

by sand are in good condition.

Concerning the mosaics,
for example, we can see some

small holes that don't look
so dangerous for the artefacts,

but if we analyse with
a microscope these holes,

we will see that inside
the tessera, inside the stone,

the hole is not small
but it's big, large.

And the monitoring of the site
is the solution of this.

At the Archaeological Museum
of Campi Flegrei, one piece

of artwork after another shows
the damage animals can do.

While it's common to see
ancient Roman statues missing

arms or heads, the items in
this collection are different.

A veiled woman has been
covered with what almost

look like pockmarks.

A base with a dedication
to Emperor Hadrian loses

all shape at the top,
like a half-melted candle.

This 74cm statue of Zeus
on his throne dating

to the first century BC
is covered with what looks

like white scrawlings -
the remnants of marine

and crustaceans.

But these organisms
weren't his only challenge.

The Zeus was likely stolen
from the sea by looters.

He wound up in the collection
of the J Paul Getty Museum

in Los Angeles, acquired
by a curator later indicted

for conspiracy to traffic
in illegal antiquities.

He was returned to the Campi
Flegrei museum in 2018.

The other sculptures
in the museum are now safe

from marine organisms.

But the artefacts that
remain below the sea,

including the precious floors
that make up the largest

collection of underwater Roman
mosaics in the world,

remain at risk.

Finally, it was time
for me to go down and see

it for myself.

I was invited to join the team
testing new technologies

to help better monitor
the erosion, but also to help

the public engage with
the site in new ways.

Chiara Petrioli is professor
of computer science

at the University of
Rome "La Sapienza",

and the interdisciplinary
project MUSAS' site

coordinator.

She is behind one of the more
ambitious aspects of MUSAS -

its underwater wireless
sensor networks.

So, what are the technologies
you're testing here this week?

This week, we are testing
underwater drones supporting

archaeologists in
discovering the site.

We are testing underwater
wireless sensor networks that

allow to gather in real-time,
data on the conservation status

of the site.

The water quality, the CO2,
because here we have very

active volcanic activity
and it's important to know

what's happening there.

And also images that we can
transmit in real-time,

compressed through novel
algorithms from the underwater

environment.

These innovations represent
a major change from how things

were done in the past.

They mean that information
and pictures about any problems

in the site, like erosion
or even looting, can be

communicated much more quickly.

Not only can underwater
archaeologists communicate

while they are diving,
but we can get data

in real-time about the site,
even when archaeologists aren't

there.

So, we have also developed
a system for divers.

On the other hand, we are able
to localise and we have

developed a way to represent
how these underwater cultural

heritage sites were in the past
using virtual reality,

so that you can actually
have an enhanced experience

visiting the site.

And you can also track
in a WhatsApp-like matter

with the rest of the divers
and with your beloved ones

on the other side of
the planet, and exchange images

or exchange your feelings,
even when you are diving.

The way this is being done
is through an underwater

Internet.

That's more difficult
than it sounds.

Wi-fi, for example, doesn't
travel far underwater.

Instead, Petrioli's team
came up with the idea

of using acoustics inspired
by marine mammals.

So, you have to use
a completely different way

of communicating, for very
short range, a few metres,

which is short-range
in this environment,

you can use wireless optical.

But mostly you have to use
the way of communicating

of marine mammals.

So, you need to use
acoustic communication.

And this is really challenging
because the sea parameters may

change.

The temperature
and salinity change.

And this affects the way
communication works.

And it's also, you know,
a ship passing by, like,

we have right now or water
motorbike, this affects

the ability to communicate.

Even the wind rising
so that the surface provides

changes, affects the
communication, then two devices

are no longer able
to communicate.

So, it's very complex,
but we came up with an idea.

Let's have mesh networks,
like, multi-networks,

and let's use artificial
intelligence techniques

to keep changing.

The product we use, the route
the information flow has to go

through, the parameters
of our communication system.

And we came up with some novel
fundamental understanding,

and it works.

What was not possible before
is now possible in terms

of performance, transmitting
even multimedia information

like images, in terms of real
ability of communicating.

And this is a gorgeous
application in underwater

cultural heritage, but this
is going to change actually

whatever we are able to do
in terms of exploring

and understanding these
environments across the blue

economy.

Under the water,
a whole world opens up.

The sculptures
here are replicas.

The real ones are safe
above ground in the nearby

archaeological museum.

But the other artefacts,
from the walls to mosaics,

are original.

As we swam, statues began
to appear out of the water.

This was the nymphaeum
of Emperor Claudius,

a place where the first century
ruler would have strolled

and admired his sculptures.

I pressed a button on my
tablet and held it up.

A 3D version of how
the nymphaeum would've looked

appeared on screen.

This is one of the other
main goals of MUSAS -

to help divers understand
and appreciate the ruins

they're looking at.

But the best was yet to come.

My dive guide, Enzo Maione,
stopped on the sea floor

and started to push
the sand around.

With each sweep of his hand,
more of the mosaic revealed

itself until we were hovering
over an intricate pattern

of circles and hexagons.

This was once the floor
of a room just off the atrium

of a magnificent villa dating
to the second century.

There's nothing quite
like seeing ancient

ruins like this.

For one thing, there's
the eerie silence of being

underwater - hearing
only your own breathing.

For another, there's
the intimacy.

Forget the crowds at sites
like the Colosseum, down here,

where only scuba divers can go,
you can experience this ancient

landscape almost alone.

And knowing that it's
being protected for future

generations couldn't
be a better feeling.

The team installed
the monitoring system at Baiae

permanently in summer 2020.

The project is also
being unrolled elsewhere,

including at an ancient
underwater site in Puglia.

It's a privilege to see it
all in person and to learn how

these innovations could
dramatically improve the way

the site is preserved
by archaeologists and

experienced by travellers.