Curbed takes a quick look at a number of underground cities around the world. I’ve highlighted a few – the ones that were not constructed for defense purposes:
SubTropolis (Kansas City, Missouri)
Hardly hidden—the development has its own logo—this huge warren of business parks carved into ancient bluffs that line the Missouri River claims to be the world’s largest underground storage facility and business park. Since opening in 1964, this constantly expanding operation, carved into former limestone mines and expanding at roughly 3.2 acres a year, has become a massive commercial success, attracting tenants such as Postal Service, the EPA, a cloud computing company, a food processing plant, and even a special firm that stores old film reels. Turns out giving up sunlight has plenty of business advantages; underground living means a constant temperature, virtually eliminating heating and cooling bills...
Underground City (Montreal, Canada)
Recently renamed RÉSO, a play off the French word reseau (network), this huge tunnel complex spread out underneath Quebec’s biggest city is a lot more utopian than many of the other entries on the list. The city, which now counts 20 miles of tunnels and more than 120 surface entry points, began in 1962 as passageways around and through the Place Ville-Marie, a shopping mall designed by I.M. Pei that helped hide an unsightly former rail depot. Decades later, it has expanded into a massive shopping a recreation district, including a hotel and hockey rink, and stands as one of the city’s busiest neighborhoods, most popular tourist attractions, and an escape from winter weather...
Helsinki Underground City (Helsinki, Finland)
In a bid to develop within its limited footprint, this Finnish city decided to build underground a few years ago, linking shopping centers and a metro station. Currently, a swimming pool, hockey rink, and church can all be found below the surface. Construction stretches nearly 100 feet below the surface, and the city has a master plan for roughly 200 new underground projects in the works, hoping to connect the region and expand space for industrial facilities, leaving the surface free for more aesthetically pleasing development.
These are quite different from abandoned facilities; these are locations that intentionally have sought out underground space for social activity. At the least, these take advantage of space that otherwise would not be used. Land is expensive in many cities so finding new space – same location, just underground rather than building up – can be quite advantageous. Additionally, such spaces can block out weather and utilize natural cooling and heating. I also imagine the underground status gives them some extra measure of cool. Contrast “do you want to go to the mall” with “do you want to go to the underground mall,” particularly for tourists or teenagers. However, if every city has some underground area (just like if every one has an elevated park like the High Line), they all may become less interesting.