Paris has a deeper and stranger connection to its underground than almost any city, and that underground is one of the richest. The arteries and intestines of Paris, the hundreds of miles of tunnels that make up some of the oldest and densest subway and sewer networks in the world, are just the start of it. Under Paris there are spaces of all kinds: canals and reservoirs, crypts and bank vaults, wine cellars transformed into nightclubs and galleries. Most surprising of all are the carrières—the old stone quarries that fan out in a deep and intricate web under many neighborhoods, mostly in the southern part of the metropolis.
These sections of caverns and tunnels have been transformed into underground ossuaries, holding the remains of about 6 million people. Opened in the late 18th century, the underground cemetery became a tourist attraction on a small scale from the early 19th century, and has been open to the public on a regular basis from 1874.
The official name for these subterranean veins is l’Ossuaire Municipal. Although the cemetery portion covers only a small section of underground tunnels comprising “les carrières de Paris”, Parisians today often refer to the entire tunnel network as “The Catacombs.”