Secrets of the Louvre:
Hidden Halls and Treasures

The Louvre is the most visited museum in the world, welcoming 8.7 million visitors in 2024. According to the museum’s administration, the exhibition occupies 72,735 square meters across 403 rooms, and the inventory books contain over 615,000 items. About 35,000 are on display to the public. The rest are kept behind closed doors.

And there lies the dry bed of a medieval moat, technical galleries branch out, and an ion beam laboratory operates. Two hundred kilometers north of Paris, near the town of Leuven, the museum maintains a second home for a quarter of a million objects. The facades along the Seine stretch for hundreds of meters, and behind many windows, services are taking place, rarely noticed by visitors.

Some of the hidden spaces were only recently revealed: in 2021, after a lengthy restoration, the public was allowed into Anne of Austria’s chambers. Other corridors are still patrolled by guards with key rings. As many legends have settled here as inventory numbers.

Fortress under the courtyard slabs

The first secret lies literally underfoot. In 1190, King Philip II Augustus, preparing for the Crusade, ordered the construction of a stone wall around Paris. The Louvre stood in the northwest corner of the city’s fortifications, facing the Seine. Construction lasted until 1202, during which time a veritable fortress arose on the plain: curtain walls, as the walls between the towers are called, 78 and 72 meters long, four round towers at the corners, and a massive keep in the center.

The donjon, the main tower, contained the entire design. The base diameter was approximately 11.7 meters, the masonry was over three meters thick, and the height reached thirty meters. The outpost’s mission was straightforward: to block the river route to the northwest, where the Plantagenets, the rulers of Normandy, were awaited. The garrison overlooked both the crossings and the river itself. A moat stretched in front of the walls.

The military significance quickly faded. In 1527, Francis I ordered the keep demolished: the tower interfered with the plans for a Renaissance palace. The moat was filled with construction debris, and the circular foundation was submerged under the slabs of a new courtyard.

It was only four and a half centuries later that it was finally brought to light. Excavations beneath the Cour Carrée, which lasted from 1985 to 1989, removed layer after layer, revealing a ditch with two corner towers and the lower tier of masonry of the keep, preserved beneath later slabs. The museum could have filled the pit with concrete and continued construction. Instead, the underground level was rebuilt around the finds, and the construction site was transformed into an archaeological showcase. The "Medieval Louvre" exhibition was first shown in 1993 and has since been reassembled several times.

The Cour Carré courtyard itself had long since become a formal courtyard by then. The square, approximately 120 meters on a side, was built in the 16th and 17th centuries, and the excavation measurements read like a table of eras: the foundations of wings, wells, and traces of outbuildings lie at their own levels. Stones from each period remain in place.

Halls that survived the fire

The west wing still has a donjon. The Salle Saint-Louis was built in the 13th century: the ribbed vaults, or stone ribs between the formwork, rest on massive pillars, and the floor is level with the old courtyard. Adjacent is the Salle des Caryatides, decorated in the 1550s according to the design of the architect Pierre Lescot. Four stone figures by Jean Goujon support the musicians’ platform; the sculptor took inspiration from antiquity, and the court of Francis I danced under these vaults at balls.

The fire of May 1871 was closing in on the wing. The neighboring Tuileries Palace, built in 1564 for Catherine de Medici and integrated with the Louvre over three centuries, burned. The Salle des Caryatids survived, as did the two outer pavilions, the Flore and the Marsan. The Tuileries burned to the ground.

The ruins towered over the city for twelve years. Paris debated the palace’s fate, and statesmen delayed a decision until the remains were finally dismantled in 1883. The Carrousel Gardens, now a tourist route to the Arc de Triomphe, were laid out in the empty space. The garden grew where the royal bedrooms once stood.

Peace after centuries of silence

The south wing, with windows overlooking the Seine, houses the chambers of Anne of Austria. After the court’s return from exile in 1652, the Queen Mother and her children lived here; the young Louis XIV used the adjacent rooms. The artist Giovanni Francesco Romanelli painted the ceilings in 1655–57, commissioned by Cardinal Mazarin; one of the rooms was nicknamed the "Golden Cabinet" for its gilded decoration.

The enfilade, or halls lined up in a row with doorways, has had a turbulent history. The halls have served as offices, warehouses, and staff apartments; the public was not allowed in for decades, and the ceiling lamps looked down on the accountants. Restorers removed the soot and later overpainting from the paintings and restored the gilding to the panels. In July 2021, the enfilade was opened to visitors for the first time in many years. Tours are now available through the halls, and the gilded ceiling lamps are once again visible from the floor.

Large gallery with rear doors

In 1595, Henry IV ordered the Louvre to be connected to the Tuileries by a covered promenade along the waterfront. Construction was carried out in two sections: Louis Métezeau built the eastern half, and Jacques II Androuet du Cerceau built the western half. By the early 17th century, the courtyard had a covered promenade approximately 460 meters long, right next to the water. Courtiers strolled between the palaces without being exposed to mud or rain; the gallery was popularly known as the "gallery by the water," and for a long time it was considered the longest in Europe.

A fire in February 1661 destroyed the neighboring Petit Galerie. In its place, Louis Le Vau erected a new space with a solar program for the young king, the future Apollo Gallery. Charles Le Brun only managed to partially paint the vault: the court moved to Versailles, and work halted for nearly two centuries. The ceiling was completed by Eugène Delacroix, who ascended the scaffolding to the vault in 1851 with his composition "Apollo Defeating Python."

The gallery also had a private, rather than a formal, side. Since the early 19th century, some of the rooms along it and under the roof have been reserved for artists: apartments, studios, and storage rooms for stretcher bars. Copiers with their easels take up their positions in the mornings, and now the museum issues them permits through a competition. Doors to storage rooms and studios are hidden in the piers; visitors pass by without noticing them.

August 1939 emptied the hall in a matter of days. Then came a German newsreel: soldiers leisurely marching through a long, empty space, frames removed, pale rectangles where canvases had hung looming on the bare walls. After the Revolution of 1793, this very film became the new museum’s first exhibition space, lit from above by glass rooflights. Today, Italian paintings hang along the walls, and the exit at the far end still leads toward the Tuileries Garden.

Inner City

Until the mid-20th century, the Louvre existed within itself, like a city block. The attics and remote outbuildings housed caretakers’ and watchmen’s apartments; long-time residents recalled dishes in the kitchens, children in the courtyards, and palace cats. Service staircases led to the halls via separate passages, and the night guards had their own keys and their own routes. Technical tiers with air ducts, cables, and walkways for navigating the glass roofs still extend above the state rooms.

Institutions have long been integrated into this lifestyle. Since 1882, the Louvre School has operated in the palace: classrooms, a library, its own lecture halls, and a line of students waiting for morning classes. The museum employs over two thousand people, and each department has its own corridor layout. Artists were evicted from the attics by the end of the 19th century, and the palace’s residential life was wound down over the decades, with the last tenants being resettled in our time.

The word “city” here is devoid of metaphor: its own streets, its own apartments, its own residents.

Augustus, who emptied the halls

The Munich Agreement of September 1938 turned out to be a rehearsal for France. Within days, the masterpieces were taken to the Château de Chambord and, once the crisis was over, returned to the walls. The evacuation plan had been tested and was stored in safes.

On August 25, 1939, the Louvre closed. Jacques Jaujard, director of the national museums, set in motion a predetermined system: a number, an inventory, and a shipping crate for each item. Lists of valuables were compiled from catalogs, items were moved in order, with masterpieces going first.

According to the management’s reports, 3,691 paintings were removed from the halls during the first days of August, and by the evening of September 3, when France declared war on Germany, the storage facilities were empty, and the plan worked exactly as it was written on paper.

A special crate with soft padding and shock absorbers was commissioned for the Mona Lisa. René Huyghe, the paintings’ curator, traveled alongside the panel. The route was structured as a series of refuges: Chambord, then the Loc-Dieu Abbey in the southwest, and finally the Château de Montal in the Lot, where the panel survived the winter of the Occupation. In 1945, the Mona Lisa returned to Paris.

Meanwhile, Chambord became a transit hub. Crates were collected from Parisian museums, students from the École du Louvre sorted the acquisitions, and sent them to the châteaux and abbeys of the Loire and the southwest. The collection was deliberately dispersed: one center held one portion of the holdings, so that no one disaster would overwhelm the entire collection. An inventory sheet was included with each crate, and using these sheets, the collections were reassembled without loss.

The containers were marked with numbers, not names. Zhozhar kept the plan secret even from some of the employees; the lists circulated only within a small circle. Employees carried the boxes out by hand; the first convoys of trucks departed in the last days of August.

The French emptied the national collections themselves, and this saved them. The Germans targeted mainly private collections. Count Wolf-Metternich, an officer in the monuments protection service, entered into closed negotiations with Jaujard regarding the fate of the warehouses and delayed the requisitions; he was removed in 1942. The halls were reopened in 1944–1945, and the losses were counted by name.

Unpaid keeper

The occupation authorities set up a staging area for looted goods in the old Jeu de Paume museum on the other side of the Tuileries Garden. Confiscated private collections were transported there, sorted, and distributed throughout the Reich. Rosenberg’s operations staff handled the inventory, while Reichsmarschall Göring personally visited to select stones and paintings.

Rose Valland, an art historian with the modest job of museum secretary, remained at the warehouse. She received no salary from the occupiers and worked voluntarily for four years straight.

"I ended up here by chance. I stayed of my own free will," she later wrote in her book, "The Art Front."

Walland’s notebooks kept a hidden ledger of the disaster: train numbers, recipient addresses, and shipment inventories. Some of the data was channeled through the resistance. After liberation, her notes helped locate storage facilities in Neuschwanstein, Bavaria, and the Alt-Aussee salt mines in Austria, where Hitler’s future museum collection lay in wait. For this work, Walland was awarded the Legion of Honor.

According to German inventories, over twenty thousand works passed through the warehouse. Many were returned, but not all found their owners. The national museums of France hold over two thousand works marked "MNR," recovered after the war; until a legal heir is named, the work is listed as being in temporary storage. The lists are published, the search continues to this day, and such labels can still be found on frames in the Louvre.

The city beneath the Place du Carrousel

In 1981, President François Mitterrand announced the "Grand Louvre" project: the Ministry of Finance was evicted from the north wing, and the museum occupied the entire palace. The ministry had been housed there since the 1870s and moved to Bercy in 1989. In the fall of 1993, the Richelieu Wing opened with 165 new rooms, including Napoleon III’s state apartments with Second Empire furnishings.

Before the renovations, the Napoleon Court served as a parking lot, with cars parked right next to the old facades. In 1988–1989, a glass pyramid, 21.65 meters tall and 35 meters on a base, was erected in the center of the courtyard, designed by architect Yeoh Ming Pei. It was composed of 673 segments: 603 rhombuses and 70 triangles. Pei called the pyramid "the form of our time" and insisted that it best suited the palace’s strict geometry. Descending a spiral ramp leads to Napoleon’s underground hall.

Downstairs are cloakrooms, a ticket office, a lecture hall, a shop, and restaurants. Nearby is the Carrousel shopping center with a bus station for tourist buses. Three lines branch off from the concourse, to the Denon, Richelieu, and Sully wings, making it easier to get lost downstairs than upstairs.

Construction was carried out while the museum was still open: halls were closed one by one, and visitors had to walk around the scaffolding. Excavations under the courtyard were combined with concrete work; the archaeological layer was part of the project from the very beginning. Some workshops and laboratories were also relocated. The pyramid wasn’t immediately accepted by the city’s residents; newspapers and Parisians, accustomed to an empty courtyard, voiced their opposition.

In 1993, an inverted pyramid was lowered beneath the square: a glass tent rising downward, its tip pointing toward the floor. Only a low glass mound in the Carrousel Gardens reveals it from the surface. The old storage rooms remain beneath the palace, in the damp vicinity of the river. Service tunnels branch out beneath the courtyard, connecting the wings, bypassing the public, and security patrols them 24 hours a day.

Accelerator under the museum

The restoration workshops and laboratories of the C2RMF center, a scientific division of French museums, operate beneath the Jardin du Carrousel. Here, paint layers, varnishes, and pigments are studied; the center’s projects include a layer-by-layer analysis of the Mona Lisa’s finest glazes, carried out without a single scratch on the panel.

In the underground hall stands a unique machine, the AGLAE ion accelerator, the world’s only particle accelerator operating within a museum. Its name stands for Grand Louvre Accelerator for Elemental Analysis. The first version was installed in 1988; the updated version was built in 2017 with support from the European Union, integrated directly into the existing galleries. The machine accelerates protons and light ions to energies of several megaelectronvolts.

The beam touches a microscopic area of paint, the atoms emit a characteristic X-ray glow, and the spectrometer translates the light into a list of chemical elements in minutes. There’s no need to take a sample, and the object never leaves its pedestal; the upgrade allows for irradiation of objects directly in the air, without a vacuum chamber. In the laboratory, this method is referred to as ion beam analysis. This is how bronze, ceramics, enamel, and paintings from collections across the country are analyzed. The doors of these halls are open only to specialists.

Reserves in Leuven

The Seine is nearby, and the river makes its presence felt regularly. The 1910 flood inundated the Parisian embankments; in early June 2016, the waters rose again, and the museum closed briefly and began emergency removal of its collections from the lower floors. The waters subsided to a critical level, and the lesson was postponed.

The answer lay in the north of the country. In 2019, near the town of Leuven, adjacent to the Louvre-Lens branch, a 20,000-square-meter underground storage facility was opened. Around 250,000 objects are being moved there gradually, each individually packaged; the climate is maintained automatically by the mass of concrete and the thick walls. The Lens branch takes items from there for its rotating exhibitions. The river doesn’t reach Leuven.

The Apollo Gallery and the Diamond Treasury

The gallery’s vault is painted in the solar program of the young Louis XIV: the theme was set by Charles Le Brun, and the ceiling was completed by Delacroix. In the early 2000s, the hall was closed for a major restoration for approximately three years: the structure was reinforced, the vault was cleaned, and the display cases were renovated. Since the late 19th century, the crown’s precious treasury has been housed here, and its history is replete with disappearances.

The treasury nearly disappeared in September 1792, at the height of the revolutionary turmoil, when a shipment of the finest stones, including the Regent, the Sancy and the Blue Crown Diamond, was stolen from the royal vault at Garde-Meuble in a matter of nights.

After those turbulent years, the largest stones were dispersed to different locations.

The story of the "Regent" reads like an adventure novel. The stone was unearthed in 1698 in the Golconda mines; legend tells of a slave who hid the find and was killed for it. Governor of Madras, Thomas Pitt, took the diamond to Europe, and in 1717, it was purchased by the Regent of the Kingdom, Philippe d’Orléans, who gave the stone its current name. The diamond was affixed to the crown of Louis XV; it is now set into the pommel of Napoleon’s consular sword, which is on display there.

The 1792 theft scattered the treasures for a long time. The Regent reappeared a year and a half later, according to popular theory, in a hiding place near Paris. The Blue Diamond was the most permanently lost and resurfaced in London, already reshaped; it is now called the Hope and hangs in a Washington museum. The Sancy passed through private hands: Prince Demidov, London and Bombay transactions, Lord Astor bought the stone in 1906, and in 1978 the Louvre returned it through a national subscription, joined by thousands of donors. The Hortense was named after Hortense de Beauharnais, Napoleon’s sister-in-law.

Cardinal Mazarin bequeathed his own diamond collection to the crown, and it is still called the "Mazarins." In 1887, the Third Republic auctioned off most of the treasury, considering the crowns a legacy of the overthrown monarchy; collectors flocked from all over Europe. A few pieces survived, including the 1722 crown of Louis XV, the only crown of the French kings of the Old Regime to survive. For the auction, the real diamonds were removed, and replicas are now mounted.

All the main buildings are behind bulletproof glass in the display cases. The display cases are bulletproof.

Mona Lisa: disappearance, pursuit, display case

Early Monday morning on August 21, 1911, when the museum was closed to the public, former glazier Vincenzo Peruggia removed the panel from its mountings and carried it out the service door under his work shirt. He took it from the Salon Carré, the entrance hall to the Grand Gallery. The painting is modest in size: 77 by 53 centimeters.

Peruggia had worked at the Louvre as a glass installer and knew the halls by heart. The theft was discovered by the artist Louis Béroud, who had arrived that morning to sketch a painting from a nearby canvas. The police examined the display case, and forensic scientist Alphonse Bertillon collected fingerprints, which led in many directions. The panel lay in the thief’s Parisian apartment for two years, in a suitcase with a false bottom.

The empty wall attracted crowds like a new attraction.

In December 1913, Peruggia took the painting to Florence and contacted the director of the Uffizi Gallery; negotiations ended with a police summons. In his response to the judges, he cited Italy and its right to reclaim the Leonardo. The court sentenced him to just over a year, and the thief served about seven months. In January 1914, the Mona Lisa returned to Paris. The poet Apollinaire was arrested and Picasso was interrogated in connection with the case; both were found innocent.

Its current home is the Salle des Nations, the museum’s largest hall. In 1956, the panel was first doused with acid, then hit with a stone, and after these incidents, the painting was covered with glass. It now sits in a sealed display case: the temperature is around 20°C, the humidity around 50%. According to the museum’s estimates, up to twenty thousand people pass through the case each day. A cup in 2009, a cake in 2022, a soup in 2024: the glass absorbed the impacts. Technicians service the case from the rear, and this access is closed to the public.

Myths about glass and numbers

The pyramid became steeped in numerical mystique. A rumor circulated around the city that President Mitterrand ordered exactly 666 pieces of glass in honor of the number of the beast. The true count is different: 673 segments, and the museum officially confirms this. Dan Brown’s novel spread the legend around the world, adding an inverted pyramid to the plot of the treasure beneath the tip. The museum took a relaxed approach to literature: in 2006, the novel was sold at the museum kiosks, and an audio guide led listeners through the fictional sites. Guides still hear questions about 666.

The name "Louvre" itself remains obscure. Older theories linked it to the wolf, lupus, as if hunting dogs were kept there; another hypothesis derives the word from the Frankish language meaning "fortress." Historians disagree.

The Tower Where the Library Came to an End

In the 14th century, the fortress was expanded into a residence. After the Parisian merchants’ revolt of 1357–1358, when the merchant provost Étienne Marcel seized control of the capital, the Dauphin Charles, the future Charles V, rebuilt the old castle with new buildings, adding towers, gardens, and a second moat. The work was supervised by the architect Raymond du Temple; a chapel, the queen’s chambers, and reception rooms were added inside. The king moved here from the Hôtel Saint-Paul.

A royal library was also assembled at this court. About a thousand manuscripts were kept in one of the towers, known as the Sokolnichnaya. In 1373, the curator, Gilles Mallet, compiled an inventory of the collection.

"Inventory of the books of our sovereign the king, kept in the Louvre castle," is how Gilles Mallet’s document from 1373 opens.

The count amounted to over nine hundred volumes, a remarkable figure for the 14th century: no private collection in the kingdom could compare. The king read Latin and commissioned scholars to translate it, including the works of Aristotle as rendered by Nicolas Oresme.

Then the dispersal began. Heirs pawned volumes, donated them, and carried them away; by the beginning of the 15th century, only remnants remained in the tower. The descendants of the collection dispersed across Europe, and the old inventory survived in the archives. Researchers use it to identify Louvre manuscripts in collections around the world; some volumes settled abroad as early as the Middle Ages. Inventories were kept according to a strict format: the name of the work, the scribe, the number of sheets, the binding. The identification method boils down to verification: the composition of the parchment, the scriptorium handwriting, the drawings of initials, traces of medieval inventories.

The library’s thread, however, hasn’t been broken: the palace houses the central library of French museums, with its own shelves and a waiting list of readers. Each new discovery of a medieval tome begins with the year 1373 and ends on the curator’s desk with a magnifying glass.