Subterranea (geography) - Subtopics

Underground lakes Subterranean fiction Burials Sinking rivers Subterranean rivers Petra Semi-subterranean structures Urban exploration Ancient Roman tombs and cemeteries in Rome Chthonic beings Rock-cut architecture Caves Mines Subterranea of the United Kingdom Manholes Subterranean warfare Subterranean buildings and structures Subterranean waterfalls Trenchless technology Underground construction