A City Buried Under Its Own Past
By the 17th century, Paris faced a growing crisis beneath its bustling streets. Cemeteries were overflowing, leaving corpses exposed and creating unbearable odors across entire neighborhoods. The worst conditions were near Les Innocents, the city’s oldest and largest cemetery.
Residents complained constantly, and even perfume shops reported they could not operate because of the smell. The crisis grew so severe that it would ultimately reshape the city beneath the surface.
From Quarries to Ossuaries
In 1763, King Louis XV banned burials inside Paris, but resistance from the Church delayed any action. It was only in 1780, after heavy spring rains caused a wall around Les Innocents to collapse—spilling decomposing bodies onto neighboring land—that the city responded.
Officials decided to move the remains into a vast network of ancient limestone tunnels, originally dug in the 13th century to build Paris. In 1786, the transfer began, starting with Les Innocents, and continued for 12 years. By the end, the bones of 6 to 7 million people, some dating back to the Merovingian era over 1,200 years ago, were relocated into the catacombs.
History Carved in Stone and Bone
During the French Revolution, burials began taking place directly in the catacombs’ ossuaries. Among those believed to rest there are figures tied to this turbulent period, including Jean-Paul Marat and Maximilien de Robespierre.
Work on moving remains stopped in 1860, but the catacombs had already become one of the largest ossuaries in the world. Inside, bones are carefully arranged, grouped by their original cemeteries, and sometimes set into decorative patterns like crosses and arches. Visitors can also find sculptures in the Port-Mahon corridor, carved by a quarryman named Décure, a former soldier in Louis XV’s army, who depicted a fortress where he was once imprisoned during the Seven Years’ War.
Exploring the Empire of Death
Today, about 1.5 kilometers of the catacombs are open to the public. The entrance is in the 14th arrondissement, at 1 avenue du Colonel Henri Rol-Tanguy, and a full tour takes around 45 minutes. Above the ossuary entrance, visitors pass under a stone arch bearing a chilling inscription: “Arrête, c’est ici l’empire de la mort!” (“Stop! This is the empire of death!”).
While the open section is only a fraction of the tunnels’ total length, which stretches for miles beneath Paris, exploring unauthorized areas is strictly forbidden. The catacombs remain one of the city’s most visited historical sites, offering a unique passage through Paris’s layered past.
Paris faced a grave crisis underground.
By the 17th century its cemeteries overflowed, exposing bodies and stench.
The answer lay in medieval quarry tunnels below.
In time, the remains of about six million people were placed there, forming the Catacombs…🧵👇 pic.twitter.com/OQOBarGQdZ
— Fascinating True Stories (@FascinatingTrue) August 26, 2025