Fontanelle Cemetery

The Fontanelle cemetery in Naples is a charnel house, an ossuary, located in a cave in the tuff hillside in the Materdei section of the city. It is associated with a chapter in the folklore of the city. By the time the Spanish moved into the city in the early 16th century, there was already concern over where to locate cemeteries, and moves had been taken to locate graves outside of the city walls. Many Neapolitans, however, insisted on being interred in their local churches. To make space in the churches for the newly interred, undertakers started removing earlier remains outside the city to the cave, the future Fontanelle cemetery. The remains were interred shallowly and then joined in 1656 by thousands of anonymous corpses, victims of the great plague of that year.

Sometime in the late 17th century—according to Andrea De Jorio, a Neapolitan scholar from the 19th century, great floods washed the remains out and into the streets, presenting a grisly spectacle.

Source: Wikipedia