What are they? We have pagan catacombs, Jewish catacombs, and Christian catacombs. But one of the things we do see in the middle of the third century is there's a growing [number] of Christian ...

Probably there are a number of lost catacombs, too." The oldest tunnels date back to the first century. "The Jewish community in Rome built them as cemeteries. Christian catacombs came a century ...