National Geographic Society

Catacombs such as these were carved over hundreds of years beginning in the second century A.D. from soft rock beneath the outskirts of Rome. The labyrinthine corridors of these underground cemeteries cover hundreds of acres and house the remains of hundreds of thousands of mainly Christians but also Jews.

At the time, burials were not permitted within Rome, and land outside the city was expensive. Several Christian landowners, however, allowed access to their property for the underground burials, and thus the catacombs came into being. Christians have also used the sites for worship and to celebrate the anniversaries of their martyrs.