The Catacombs of Paris are underground ossuaries in Paris, France, which hold the remains of more than six million people in a small part of a tunnel network built to consolidate Paris' ancient stone quarries. Extending south from the Barrière d'Enfer former city gate, this ossuary was created as part of the effort to eliminate the city's overflowing cemeteries. Preparation work began not long after a 1774 series of gruesome Saint Innocents-cemetery-quarter basement wall collapses added a sense of urgency to the cemetery-eliminating measure, and from 1786, nightly processions of covered wagons transferred remains from most of Paris' cemeteries to a mine shaft opened near the Rue de la Tombe-Issoire.