In 1785, Paris decided to solve the problem of its overflowing cemeteries by exhuming the bones of the buried and relocating them to the tunnels of several disused quarries, leading to the creation of the Catacombs, basically corridors stacked with bones. They are 65 ft (20 m) underground and contain the remains of six million Parisians. During WWII, the tunnels were used as a headquarters by the Resistance.
The route through the Catacombs begins at a small, dark green Belle Époque-style building in the centre of a grassy area of av Colonel Henri Roi-Tanguy, the new name of place Denfert Rochereau. The exit is at the end of 83 steps on rue Remy Dumoncel, southwest where a guard will check your bag for 'borrowed' bones.