NOVA

Notre Dame de Paris...

A treasured icon of Gothic architecture

and medieval engineering,

built from glass,

stone,

and timber over the course

of two centuries.

For 850 years, this 226-foot-tall cathedral

has been an enduring symbol at the heart

of French culture, and more...

Notre Dame is one of humanity's greatest

artistic and architectural achievements.

Notre Dame is not just Paris.

It's France.

And beyond France,

it's the world.

But on April 15, 2019,

a disaster that threatens to destroy it all strikes.

A massive fire raging out of control...

Oh, my God!

Leaves the cathedral in ruins.

Now, an elite team of engineers,

scientists,

and master craftspeople,

battle to save this fragile structure

from a catastrophic collapse.

Out of tragedy, an opportunity is born...

Oh!

This is a dating fossil.

To solve archaeological mysteries

and understand the very fabric

of this medieval megastructure

like never before.

We can identify each chemical element.

Can clues from the past

help save and rebuild this landmark?

And can pioneering technology

prevent another disaster?

What we are producing today

will be the information usable for the next generations.

"Saving Notre Dame"...

right now, on "NOVA."

Major funding for "NOVA" is provided by the following:

The Cathedral of Notre Dame de Paris...

an 850-year-old Gothic wonder.

It's the heart of France.

The distance from Paris to all other places

is traditionally measured from this iconic structure.

There is a continuation,

a historical continuation,

from the Middle Ages to nowadays.

And it's very important to build a kind of identity.

Notre Dame is one of the monuments

which achieved this identity.

For Christians, it's a place of worship, right?

And, and for those of us with different beliefs,

it's one of just this incredibleartistic and historic landmark.

You've had coronations there,

you've had the crowning of Napoleon and King Henry.

There's just so much attached

to the cathedral.

But Notre Dame is much more than that.

It's also a pinnacle of medieval engineering.

The cathedral can hold 9,000 worshippers,

and its 100-foot tall walls

contain more than 32,000 square feet of stained glass.

The ceiling is a series of domed Gothic vaults

that hold up the cathedral from the inside.

A complex 550-ton web of timber

forms a cross-shaped roof,

topped with 1,300 lead tiles

and a 300-foot tall central spire.

Wrapped around the church are 28 flying buttresses,

limestone arches that brace the walls from the outside.

And at the front, two mighty towers,

with ten massive bronze bells inside,

soar over 226 feet into the sky over Paris.

The construction took many generations.

Architecture was not learned at the university,

so the architects and allworkers learned mostly on site.

Along the way, there were many setbacks.

In 1789, at the height of the French Revolution,

anti-Catholic forces

destroy parts of the Cathedral.

A newly secular France leaves Notre Dame

in a state of neglect.

But when Victor Hugo writes "The Hunchback of Notre Dame"

in 1831, it sparks a $60 million restoration,

that tops out the cathedral with a new roof

and a 750-ton timber and lead spire.

Periodic renovations continue to this day.

On April 15, 2019,

Notre Dame is wrapped in 550 tons of scaffolding,

as workers begin

a $6 million operation toshore up the cathedral's spire.

Notre Dame's rector,

Father Patrick Chauvet,

has finished evening worship.

His world is about to be turned upside down.

I stopped here because

I really like Mado.

She offered me a drink, and when she came back she said,

"Father, there's smoke above the spire of the cathedral."

So I left my drink and went back to check there was nobody

in the cathedral.

At 6:18 p.m., a sensor detects smoke

in the medieval roof timbers.

The system sends a coded fire alert to the security team.

Instead of heading straight for the roof,

a guard is dispatched to the sacristy building nearby,

to check for a fire.

But he finds nothing.

He climbs up into the church attic.

But by the time he gets there, he's too late.

The fire has been burning for almost 30 minutes

and has spread across the roof.

And there was this horrifyingly

huge plume of smoke billowing up out of it.

It was surreal.

I'd never seen anything like that before.

You saw the fire trucks come up

alongside the cathedral and ladders went up,

and the hoses came out, you could see that the ladders

were just too small for a building of this size

and the hoses were not nearly big enough

for this kind of blaze.

It was tragic; the resources

that were available were not going to be

what was needed to bring this thing under control.

A lot of us realized

that this fire was just going to ravage the cathedral.

We saw what was happening,

but we were powerless,

we could do nothing.

It really looked like the end of the world.

It was so chaotic.

A delay in responding to a fire of this nature

is absolutely critical.

A small fire burning locally is a very different thing

than ten minutes laterwhen all of the timber elements

are involved.

So in a situation like this,

five, ten, 30 minutes can make all the difference.

This delay will have huge repercussions.

As firefighters arrive on scene,

so does one of France's chief architects

of historic monuments,

Rémi Fromont.

I managed to pass the police checkpoint

and I joined the firefighters.

As the inferno rages at the top of the cathedral,

Rémi risks his life to venture inside

with the firefighters.

We did a tour of the cathedral several times.

We checked the nave.

I saw the flames and saw the blaze.

I gave them all the advice that I could.

Within minutes, the firefighters are pumping tons of water

into the roof space,

but to no avail.

To the horror of the growing crowd,

the fire engulfs the iconic spire.

The world watches helplessly

as the 750 ton oak and lead masterpiece gives way.

Oh, my God!

Oh, my God...

That is awful.

When the spire

fell into the roof, additional ventilation

will have caused more oxygen-rich air

to be sucked in at the bottom of the compartment.

That influx of oxygen

could have caused an increase in the severity of the fire

within Notre Dame.

All of a sudden, there was a huge, huge ball of fire

rising out of the cathedral.

It was spitting ash and debriseverywhere, so we took shelter.

It was just devastating to watch.

We were suddenly really aware

that of, of how easily this whole thing could come down.

90 minutes after the fire begins,

the entire roof of the cathedral is ablaze.

Inside, it's become even more dangerous for Rémi

and the firefighters.

Getting this fire under control looks impossible.

The fire on the ground,

smoke everywhere, a hole in the ceiling.

We were trying to understand what was going on,

where the problems where, check what had collapsed

and if there were other risks.

A southeasterly wind picks up

and pushes the blaze towards the famous bell towers.

If the bell towers catch fire,

and the bells fall,

then they will smash through everything below.

Inside the ingeniously engineered

13th century north tower

a scaffold of wooden beams holds eight bells.

The biggest weighing more than four tons.

If the beams burn through,