Subterranea refers to underground structures, both natural (such as caves) and man-made (such as mines). Some subterranea include:
Bunker
Burial vault (tomb)
Casemate
Catacombs
Caves
Ice caves
Cave dweller, Underground living
Cave temple
Cellar
Cenote
Dungeon
Dugout (shelter)
Karst
Gallery
Lava tubes
Lunar lava tube
Rock cut architecture, rock grave
Smuggling tunnel
Subterranean rivers
Subterranean waterfalls
Tunnels (street tunnel, train tunnels)
Underground city
Underground lakes
Underground rapid transit systems
Volcanic pipes
Wine caves
