The paintings of the catacombs date from the third and fourth centuries after Christ. The catacombs, or burial-places of the early Christians, consist of long, narrow, subterranean passages, cut with regularity, and crossing each other like streets in a city. The graves are in the sides of these passages, and there are some larger rooms or chambers into which the narrow passages run. There are about sixty of the catacombs in and near Rome; they are generally called by the name of some saint who is buried in them.