Usually, catacombs. an underground cemetery, esp. one consisting of tunnels and rooms with recesses dug out for coffins and tombs.

the Catacombs, the subterranean burial chambers of the early Christians in and near Rome, Italy.

an underground passageway, esp. one full of twists and turns.

noun

cinerarium , crypt , mausoleum , ossuary , sepulcher , sepulture , tomb , vault , cave , chamber , grotto , passageway