An artificial cavern-like retreat.
A small cave.
A Marian shrine, usually built in a cavern-like structure.
A local organization of cavers that typically organizes trips to caves and provides information and training for caving; a caving club.
A secretive name for a local group of underground Satanists.
A cellar or vaulted storage room.
A ground-level car park that occupies the base of a building.