Prior to 1810 the Paris catacombs were known as Paris' Montrouge stone quarries. As with any large city graveyards began to quickly run out of burial space thus an alternative means of disposing of bodies was necessary.
The Catacombs, Rome, Italy. Durring the persucution of the early church, the Church hid down in the city's burial cite. Authorities were afraid to go down and get them and the ones brave enough couldn't find the Christians.