The Catacombs of Paris are underground ossuaries in Paris, which hold the remains of more than six million people in a small part of a tunnel network built to consolidate Paris' ancient stone mines. Extending south from the Barrière d'Enfer (Gate of Hell) former city gate, this ossuary was created as part of the effort to eliminate the city's overflowing cemeteries. The ossuary remained largely forgotten until it became a novelty-place for concerts and other private events in the early 19th century; after further renovations and the construction of accesses around Place Denfert-Rochereau, it was open to public visitation from 1874.