An underground cemetery made up of a succession of narrow galleries and chambers cut into bedrock. Rows of horizontal burial niches were cut into the walls for single or multiple burials. As space was needed, the catacombs were extended further underground. The Callistus catacombs, for example, had seven layers of galleries and covered over 6 miles.

A rectangular slot cut into the walls of a catacomb where bodies would be placed for burial. After a burial, the niche would be sealed with a slab of marble or terracotta.

Tablelike structures placed in burial chambers to hold offerings of food or drink when people came to the graves for banquets in honor of their family members. The tops of mensae often had depressions carved into them in the shape of the foods to be offered on them, such as fish and bread, and included basins or pipes to hold wine. Early Christians expanded the practice of eating with their dead to include others within the Christian community who had died, such as saints and martyrs.