Many far-future science fiction stories feature the concept of arcologies -- gigantic megacities or self-sustaining superstructures designed to accommodate high-density populations. It's a common trope in dystopian cyberpunk fiction, where the future is usually very crowded indeed. Arcology design principles -- the word is a portmanteau of architecture and ecology -- can be seen in city planning initiatives all over the world. For instance, Montreal's Underground City (La Ville Souterraine) has more than 20 miles of tunnels connecting apartments, hotels, office,s and shops. In 1970, architect Paolo Soleri founded Arcosanti, an "urban laboratory" in central Arizona designed as an ongoing experiment in arcology principles.