All language subtitles for a.s.s02e01.1080p.hdtv.h264-cbfm_track3_[eng]

the largest museum in the world,

visited by more than
10 million people every year.

This immense building covers
a vast 243,000 square metres,

making it the largest
architectural assemblage in France.

Today, the Louvre
is known for its Pyramid,

a monumental structure
of glass and steel.

But since its origin,

the palace has seen
exceptional technological innovation.

Eight centuries
of architectural advances

that have transformed
a simple royal residence

into the largest museum
on the planet.

The Louvre is one of the most famous
monuments in the world,

but it is also
one of the most mysterious.

And it still
hides construction secrets.

By scanning the palace,

from the satellite and aerial scale
to the molecular scale,

scientists can now unravel
the greatest mysteries of the Louvre.

Investigators will use
an advanced drone for the first time.

And conduct 3D laser surveys
of the structure...

..to reveal the secrets
hidden behind the Louvre

completely invisible
to the naked eye.

Technology will unlock the mysteries
of the Louvre's construction

and reveal the genius
of its architects,

exposing the incredible link
between the museum

and the greatest monuments of Paris.

How did builders construct
one of the world's largest palaces

in the heart of Paris?

What construction techniques
are hidden within the palace's walls?

What technical innovations allow
engineers to tunnel just 15m

beneath a building that
houses many priceless treasures?

History, science, engineering

exposed as never before.

The Louvre Palace finally
reveals itself on every scale.

The Louvre is an architectural
masterpiece in the heart of Paris.

It is one of the largest palaces
in the world

and occupies a big part
of the capital's centre.

How did builders construct
such an immense structure

in one of the most densely populated
cities in the world?

Today, satellite images
make it possible

to visualise the monument's
oversized plan in its entirety.

The Louvre Palace
and the neighbouring Tuileries estate

cover 42 hectares,

the equivalent of
40 football pitches.

So how did builders,
over eight centuries of evolution,

construct one of the largest palaces
on the planet?

To understand how this
monumental structure came into being,

it's necessary to go back
to the source of the monument

and investigate
the mystery of its origin.

A few metres below the monument,

researchers have uncovered
finely cut foundations

dating back to the 12th century.

This exceptional masonry
from the Middle Ages

is evidence of the very first
building of the Louvre.

These archaeological discoveries
shed light on the Louvre's origin.

Now, 3D modelling exposes
what the building looked like

in the Middle Ages.

Ancient builders
constructed the fortress

as a square military building,
with walls spanning 80m.

They defended its walls
with circular towers,

and built a 30 metre-high keep
at its centre,

a symbol of royal power.

The foundations are evidence
of a fortified castle

built 800 years ago by
a French king called Philip Augustus.

What's surprising is that
the same fortresses,

with the same plan
and similar construction principle

can be found in cities
all over France.

So why did so many
fortified castles in France

copy the chateau du Louvre?

The answer to this riddle

lies in examining the structure
at a macroscopic scale.

Geologists want to determine
the origin of these building stones.

Examining the stone
at a macroscopic scale

exposes mysteriously-shaped marks.

Engravings of crosses,
triangles or even hearts

can be seen all over the masonry.

These marks reveal how builders

ensured efficiency at each stage
of the construction

of this monumental fortified castle.

The building site is gigantic
for the end of the 12th century.

For the first time in France,

King Philip II's engineers
design a construction method

that can be easily reproduced.

The first Louvre
was built in just ten years,

an astonishing feat
for this period of the Middle Ages.

From the very beginning
of its construction,

the Louvre has been
a fortress of impressive dimensions.

It served as a model
for the King's castles,

but it is still far from the scale
of the present Louvre.

Examining the site
on the satellite scale

exposes the difference in size.

So how and why did builders upgrade
the imposing Middle Ages fortress

to build one of the world's
largest palaces?

The first step in this metamorphosis

was to transform a defensive castle

into a residence suitable for a king.

A branch of the palace
known as the Lescot wing

is the only building from this era
still visible today.

But at first glance,

there is nothing to differentiate
between the periods of construction.

Examining masonry
at the macroscopic scale

reveals the construction techniques
used in the Renaissance.

This Renaissance-era
masonry technique

has been found in all stages
of the palace's construction.

Builders used this hard stone
for the bases of walls and windows,

the parts of the structure
most susceptible to weathering.

But they used a different,
softer rock called Oise stone

to make up the bulk
of the palace buildings.

The royal residence,
although upgraded,

was still the same size
as the original castle.

So how did the palace transform
from a 6000-square-metre castle

into a building
20 times larger today?

Why and how did this royal residence

become the largest palace
on the planet?

Now investigators have discovered
that the fate of the Louvre

is linked to a building
that no longer exists today.

The remains of this building can
only be seen with radar technology.

Today, Thibault Sevenet is exploring
the west end of the building.

He wants to investigate the soil

underneath
the so-called 'tile gardens'

using geostatic radar technology.

The antenna sends a magnetic field
into the ground

and a receiver
records the signal that returns.

Very quickly, the radar locates
hidden remains several metres...,

foundations located between
the two wings of the Louvre Palace

over a distance of nearly 250 metres.

Examining satellite images

exposes the contours
of this ancient lost palace.

This is the Tuileries Palace,

commissioned in 1564

by the Queen Mother
Catherine de Medici,

for her personal use.

She decided to build her home
500m west of the Louvre castle,

on the outskirts of Paris,

in an area that was
still countryside at the time.

The royal residence is located
on one side of the Louvre,

and on the other, the castle
built by the Queen's mother.

It was King Henry IV,
more than 400 years earlier,

who decided to link these two castles

and transform
an entire district of Paris

for a single purpose -

to build the largest palace
in Europe.

Henry IV ordered the Great Gallery,

a 460 metre-long
and 13 metre-wide building,

to link the two palaces.

It was a huge and unprecedented
construction project for the time.

This new work
increased the Louvre's surface area.

The dimensions are breathtaking.

From the foot of the monument,

it's almost impossible
to see the end of it.

For two centuries,
the Louvre was steadily expanding.

The gigantic size of the project

required huge
financial and labour resources.

But how did the builders
supply stone to such a huge project?

The quarries in Paris and Oise
were no longer sufficient.

In 1870, the Louvre Palace
was finally completed.

At the time, it was
the largest building in France,

covering 135,000 square metres
of the capital.

Thanks to the construction
of the Tuileries Palace,

which long ago burned to the ground,

the first Louvre castle
was transformed over centuries

into a royal palace

that is the largest monument
ever built in Paris.

Today, the 243,000 square metres
of the Louvre

houses a treasure trove
of architectural masterpieces.

During each period of construction,

builders tried to outdo each other
in technical prowess

as they enlarged the monument.

But what hidden technical innovations

allowed architects to make the Louvre
appear as if it was built in one go?

Clues to this mystery
lie in examining the construction

of key parts of the Louvre,

starting with
one of the oldest parts,

the reception room
of the Lescot Pavilion.

It's one of the most remarkable rooms
of the Renaissance Louvre,

a ballroom
as large as three tennis courts.

Its dimensions are astonishing,
even today.

But there's something strange
about the layout of this room.

This is a sign that
these vaults were added

after the original construction.

But why?

A 3D reconstruction exposes
the evolution of the building.

King Henry II
wanted this reception hall

to be as large and as high
as possible,

to dazzle his distinguished guests.

His architects chose to install
a wooden ceiling.

The original grand reception hall
had a ceiling over 15 metres high.

The builders would have to find
a new way to support the ceiling.

In another, less well-known
part of the building,

there are more hidden
architectural secrets.

The best way to expose them

is to examine the structure
on a satellite scale.

With the disappearance
of the Tuileries Palace,

and the creation of the Pyramid
as the entrance to the museum,

the layout of the Louvre
has been transformed.

But a monumental and grand entrance
to the Louvre Palace

has long been forgotten.

The monument is immense -
170 metres long,

with 52 columns on the facade
that are almost 12 metres high.

How did the builders
manage to assemble these stones

and make sure
they would stay standing?

So how did the builders
achieve this architectural feat?

Clues lie high up
on the underside of the colonnade.

Access to the roof of the Louvre
is tightly controlled,

but it's the only way to study
the masonry's hidden engineering.

The latest technology can be used
to reveal what is hidden inside.

The 3D reconstruction
of the structure

exposes the full extent
of the challenge.

Engineers chose a technique
that would reinforce the stone.

They used iron as a framework
for the stone elements,

ensuring the stability
of the structure.

The Louvre Palace hides
daring and innovative techniques

at each stage of its construction.

The latest monumental achievement,

the glass pyramid,
built in the 1990s,

also conceals some well-kept secrets.

This monumental structure
is 21 metres high

and made entirely of glass and steel.

Now, for the first time
since its construction,

a technical drone is being used
to inspect the building.

The drone takes 2500 photographs
on each of the four sides,

recording detail down to 0.2mm.

A 3D scan exposes the first secret
of the Pyramid's construction.

It's formed from 603 panes of glass,

95 tons of steel

and 105 tons of aluminium -

heavier than a passenger jet.

It covers an area of
more than 1000 square metres.

But this pyramid is just a small
part of a hidden technical wonder.

The true scale
of the technical challenge

can only be revealed
on a satellite scale.

Nearly 100,000 square metres
of surface area was developed,

including an underground avenue
1.5km long and 4m wide,

which connects each
of the historic wings of the palace.

The Pyramid sits atop an underground
city built 30 years ago.

It represents just a small part
of the full construction at the time.

Its position in the very centre
of the Napoleon Courtyard

underlines the genius
of the builders of the Louvre.

Evidence suggests
that the architects of this palace

planned the layout
so that it would provide

a remarkable view for onlookers.

The Louvre is a unique monument,

once a huge royal residence,

now the largest museum in the world.

This imposing architectural ensemble
on the banks of the River Seine

is anchored by the Pyramid,

an architectural jewel
which shines in its heart,

the centre point
of a breathtaking view.

The Pyramid
and the Arc of the Carrousel

seem to line up with the obelisk
of the Place de la Concorde,

the Champs-Elysees,

the Arc de Triomphe,

and finally, the Arche de la Defense,

a perspective
of almost 8 kilometres.

This view is considered
one of the most beautiful in Paris.

How did the builders
achieve such a feat?

What's the secret
behind this lack of symmetry

in one of the most
emblematic monuments of France?

On a satellite scale,

there's a clear
6% misalignment of the Louvre,

a discrepancy so large that
it cannot be a calculation error.

So why did the architects
plan the building like this?

Geo-radar technology reveals that

the Tuileries Palace
had imposing dimensions - 260m long,

so it completely obscured the Louvre
to the west.

Today, there is nothing left
of this iconic palace.

In 1871, during a revolt
against the ruling power,

the palace was completely
destroyed by fire.

But fortunately, some elements
of the Tuileries Palace survived.

Neguine Mathieux is the Director
of Research at the Louvre

and joins Amelie Methivier,
a stone restorer,

to visit the ditches
of the Great Colonnade.

Neguine is in charge of
securing the key to this vaulted room

and for good reason.

This room contains an invaluable
treasure, kept out of sight.

Analysing these remains
exposes the ferocity of the fire.

The disappearance
of the Tuileries Palace

gave the Louvre a new layout.

Examining the site
on a satellite scale

reveals that the axis
of the former Tuileries Palace

corresponds perfectly
to the historical view of Paris.

The architect has planned the layout
in relation to the Tuileries Palace,

and not in relation to the Louvre.

But the satellite-scale images

show that this is not the only part
of the palace which is asymmetrical.

Its wings follow two different axes,
which are not parallel.

On one side, the Great Gallery,

which follows the course
of the Seine,

and on the other side,
the Richelieu wing,

which has to fit around
the layout of the streets of Paris.

The result -
the Louvre's plan is irregular.

So how did architects
conceal the anomaly?

Once again, they resorted
to a simple but effective trick.

The architects' stroke of genius
corrected the error of symmetry

when viewed from
the centre of the Louvre.

Many technical and architectural
innovations were made

during the construction
of the palace.

But as the building
neared completion,

the Louvre would undergo
a new metamorphosis.

It is known today as
the largest museum on the planet.

The Mona Lisa, the Wedding of Cana -
priceless works of art

are admired by more than
10 million visitors each year.

In the 18th century,

when it was decided to
turn the palace into a museum,

the rooms were small and dark,

reserved for the king and his court.

So how did architects radically
change the use of these buildings?

How can a royal residence

be transformed into one
of the largest museums ever built,

capable of housing priceless works
of art and millions of visitors?

From ground level at the Louvre,

there are few clues to expose

the transformation
from a royal palace to a museum.

But satellite images reveal

a radically different view
of the Louvre.

All the roofs have been opened up.

Glass canopies
cover most of the museum.

How were these openings created?

The glass canopies
provide a natural lighting source

that revolutionised the design
of museums throughout the world

at the end of the 19th century.

Investigations on a macroscopic scale

reveal that the frames are built
entirely of metal,

to support the glass canopies,

as seen at the top of
the Daru Pavilion,

one of the highest in the Louvre,

which lights a monumental staircase.

Engineers built 10,000 square metres
of glass roof.

But how did this revolutionary idea
of opening up the ceiling

and creating metal frameworks
come about?

Clues hidden in some structures

reveal that it all began
at the Louvre.

Examining the building
on a satellite scale

exposes a unique glass roof,
today inaccessible from inside.

The reconstruction of this framework
in three dimensions

reveals the historical structure.

The framework of the Salon Carre
measures 23m by 15m.

It supports a central glass roof
of 13m by 5m,

and is formed from 16 tons
of wrought iron.

By analysing the steel structure
and checking ancient documents,

experts realised that it is

the oldest surviving example
in the world,

an icon of engineering
built DURING the French Revolution.

The choice of wrought iron
for these frames

was a technical innovation
at the time.

This framework
is one of the first prototypes

of a metal-structured glass roof -

an innovative concept that would
inspire museums all over the world.

Despite the gigantic size
of some rooms,

such as the Great Gallery
or the Caryatids' Hall,

there is a lack of space
in the museum,

especially to house
monumental statues.

Clues to how architects
solved this problem

are revealed by examining
the building on a satellite scale.

In the '90s, architects decided
to cover the surface courtyards

and turn them into
huge exhibition spaces.

3D modelling techniques
expose the detail

of this lightweight structure
formed from 14cm-wide steel tubes

and supported by a network
of stainless steel cables.

The final challenge for architects

was making it invisible
from the ground,

in order to respect
the architectural integrity

of the Rue de Rivoli
in the centre of Paris.

The problem of lighting
the museum was solved.

But there's still another difficulty.

In this museum,

only a tiny proportion
of all the objects are on display.

For every square metre of space
used to show works of art,

at least twice as much
invisible infrastructure is needed.

The Louvre needed storerooms,
laboratories, offices, workshops.

But none of this originally existed,

so engineers had to dig
underground galleries.

Neguine Mathieux is exploring

the first basements
created in the Louvre.

This underground city was built
at the end of the 19th century

to allow the museum
to function properly.

In this maze of secret corridors,

some spaces have been
abandoned and forgotten.

These historic underground passages

are proof that there are still
unknown places to be rediscovered.

Investigating the Louvre's basements
provides a glimpse

of the many layers of
the monument's construction,

a series of innovations that
make the Louvre's hidden underbelly

a mosaic of diverse
building techniques.

The Louvre -

this stone colossus in the heart
of Paris seems unshakeable.

But early on, the building
did show signs of fragility,

especially the 460m-long gallery
built on the banks of the Seine.

Any movement of the building

could cause more than
just major structural problems.

Some areas of the Louvre

are built with priceless
sculpted and painted decorations

that could be damaged by the
slightest movement of the masonry.

When the human eye isn't enough

to monitor this
270,000-square-metre complex,

the latest technology is needed

to examine the monument
in minute detail.

One of the newest methods
of investigation is photogrammetry,

used today on one of the oldest

and most precious parts
of the Louvre, the Apollo Gallery,

built perpendicular to the Seine
in the 17th century.

Photogrammetry allows investigators

to create a precise
3D reconstruction of reality,

shedding new light on architectural
and decorative features.

This 3D mapping of the Louvre

exposes the evolution
of the old buildings

and helps engineers detect
the slightest structural movement.

In some places,
major cracks have been uncovered.

So what is the condition
of the Louvre's foundations?

The foundations are inaccessible,

buried several metres deep
under the building.

But today, science and technology
make it possible

to detect the invisible
and probe the impenetrable.

Now, an exceptional project
is giving engineers the opportunity

to examine
the underside of the palace.

Thanks to new
construction techniques,

they will dig under the Visconti
Courtyard in the heart of the museum,

and under part of the Grand Gallery

to create new exhibition room.

But the work has already begun.

At this exceptional
construction site,

the latest technology is used
to scan the ground

and examine
the state of the foundations.

Engineers can't afford to take risks
while digging under the Louvre,

one of the most renowned buildings
in the world.

After analysing radar readings,

the team used core sampling
at strategic points in the Louvre

to probe the subsoil of Paris.

The first revelation is that

the foundations
are much shallower than expected.

A stone building of this height

usually requires foundations
3 to 6 metres deep.

But to investigate the current
condition of the foundations,

it's necessary to change scale

and examine the stone
using an electron microscope.

These fragments
are from the core samples

taken from the basement of the Louvre

and will be examined
on a microscopic scale

to determine their nature
and properties.

Scientists use an electron microscope

to bombard an object
with a beam of electrons,

the smallest particle in an atom.

The object is
placed in a vacuum chamber,

and the wave-like characteristics
of the electron

magnify the object's image,

allowing the scientists to examine
the material at high resolution.

This microscopic study

exposes characteristics
and structure of the stone

which are completely invisible
to the naked eye.

The microscope exposes
a second revelation

about the foundations of the Louvre.

The research team discover that

the concrete under
the stone foundations is damaged.

This is a double threat
for the Louvre.

Investigations reveal that

not only are the foundations
extremely shallow,

but that the materials used
at the time have lost their strength.

The banks of the Seine
are particularly soft

and water infiltration
due to bad weather and flooding

weakens the old concrete

and endangers
some historic buildings.

Faced with these revelations,

the engineers must find a solution
to consolidate the foundations

and secure this part of the museum.

Engineers choose
a technique called jet grouting.

They drill several metres
into the ground

and then spray in
a self-hardening cement.

Hundreds of underground columns
now reinforce

the eroded foundations
of the Visconti Courtyard.

But even the most recent structures
can show signs of fragility.

The Pyramid of the Louvre
is an architectural gem,

a huge, 2000-square-metre glass roof

supported by a spider web
of stainless steel.

To study the behaviour
of this monumental structure,

investigators turn to
advanced technology

that can expose whether the Pyramid
is undergoing too much movement.

The team wait until
the middle of the night

to take precise measurements
using a laser scanner,

a technique known as lasergrammetry.

The 3D modelling reveals

that the structural elements
of the Pyramid

can undergo deformations of
several centimetres in a single day.

But the measurements also reveal

that the whole pyramid
has notably shifted.

Built over eight centuries,

the Louvre is
an iconic and unique monument

from the oldest foundations
to the most recent structures.

The latest technology
makes it possible

to study and protect this monument,

which many consider to be
the true masterpiece of the museum.

The Louvre -

this palace of kings
in the heart of Paris

is a testimony
to architectural innovation.

Eight centuries of technical daring

that have transformed
a fortified castle

into the largest museum
on the planet.

The Louvre is a museum city,

a living structure with more than
2000 employees working every day

and 25,000 daily visitors
who come to admire its works of art,

an immense machinery
that doesn't stop.

Now, new investigative tools

have made it possible to explore
this building's structure.

New technology is
also raising fresh questions

about a monument that historians
thought they knew well.

Surveying the basements
of the Tuileries

will reveal the exact nature
of the remains - maybe more -

perhaps discovering
new forgotten rooms.

The Louvre's scale is immense,
as are its component buildings,

whole sections of which
aren't yet fully investigated.

A colossus of engineering,

a true architectural masterpiece

whose design was often
ahead of its time.

Captions by Red Bee Media
(c) SBS Australia 2022