underground city
series of linked subterranean spaces
Naples underground geothermal zone
underground museum in Chiaia, Municipality 1 of Naples, Italy
East Metro Mall
shopping mall in Taipei, Taiwan
Central Government War Headquarters
underground complex in Wiltshire, England
Yokohama Porta
shopping mall in Yokohama
Ramen Street
Tokyo Ramen Street
Underground City
network of connected buildings in Montreal
PATH
network of pedestrian tunnels in Toronto
APIA
underground city in Japan
Alice City
proposed underground suburb in Tokyo