Invisible Places | 1996
Three-part special explores the hidden places underneath cities. Historically these underground structures were used as hiding places, escape routes and catacombs. Today large cities often construct underground transportation systems or hide cables, pumping systems and generators underground. The first segment "Underworld" exposes crypts, dungeons, catacombs and subterranean tunnels around the world. The second segment "Subtropolis" goes under the world's oldest and largest cities, examining their unusual infrastructures. The third segment "World of War" travels underground to the places to which people have fled for protection from nature and human enemies, ranging from hollowed-out mountains to the underground tunnels built to hide from Nazi attacks during World War II.