High Quality Content by WIKIPEDIA articles! Montreal's Underground City (officially RÉSO or La Ville Souterraine in French) is the set of interconnected complexes (both above and below ground) in and around Downtown Montreal, Quebec, Canada. It is also known as the indoor city (ville intérieure), and is the largest underground complex in the world. The lower floors of the Eaton Centre between the McGill and Peel metro stations. Not all portions of the indoor city (ville intérieure) are underground. The connections are considered tunnels architecturally and technically, but have conditioned air and good lighting as any building's liveable space does. Many tunnels are large enough to have shops on both sides of the passage. With over 32 km (20 mi) of tunnels spread over more than 12 km2 (4.6 sq mi), connected areas include shopping malls, apartment buildings, hotels, condominiums, banks, offices, museums, universities, seven metro stations, two commuter train stations, a regional bus terminal and the Bell Centre amphitheatre and arena.