Long before anyone drew an “earthscraper,” whole communities were already living, working and moving underground. Subterranean urbanism is not science fiction — it is a proven answer to heat, cold, scarce land, and the need for protection, with working examples on four continents.
Montreal's RÉSO: the underground city
Montreal's RÉSO (long known as the Underground City, or La Ville Souterraine) is the most-cited example of a modern subterranean urban network. It grew out of the 1962 development of Place Ville Marie, the cruciform tower complex master-planned with the involvement of architect I. M. Pei and developer William Zeckendorf, which put shops in a climate-controlled concourse beneath the plaza. Successive connections — accelerated by the Metro and by Expo 67 — linked building to building until the system spanned roughly 33 kilometers (about 20 miles) of pedestrian passages tying together dozens of office towers, hotels, shopping complexes, universities, and Metro stations. Several hundred thousand people move through it on a typical winter day, never touching the −20°C air above. Its entire reason for existing is climate: it lets a northern city stay open through a brutal winter.
Helsinki: the first comprehensive underground master plan
Helsinki, Finland, went a step further than any other city by adopting a city-wide Underground Master Plan — first approved around 2010 and updated since — that zones the bedrock beneath the city the way a normal plan zones the surface. Carved into the hard granite are hundreds of facilities: a swimming complex, sports halls, a running track, data centers that recycle their waste heat into the district heating grid, parking caverns, water-treatment works, and civil-defense shelters. The much-photographed Temppeliaukio Church, blasted directly into a rock outcrop and topped with a copper dome, is an early emblem of the approach. Helsinki's insight was administrative as much as technical: by planning the underground deliberately, the city avoids a chaotic tangle of one-off tunnels and reserves the best rock for the best uses.
Coober Pedy: a town that moved underground to survive the heat
Coober Pedy, in the South Australian desert, is the clearest case of climate-driven underground living. Opal mining began there in 1915, and returning World War I soldiers — familiar with dugouts — adapted the mining technique to housing, carving homes into the hillsides to escape surface temperatures that routinely exceed 40°C (over 100°F). Today a large share of the town's residents live in “dugouts” that hold a comfortable, stable interior temperature year-round with no air-conditioning. The town includes underground homes, hotels, shops, and churches — including the well-known Serbian Orthodox and Catholic dugout churches — hewn from the same sandstone.
The recurring driver: the ground never gets the memo about the weather
Coober Pedy (fleeing heat) and Montreal (fleeing cold) are opposite climates reaching the same conclusion. A few meters of rock or soil buffers a dugout in the Australian desert and a concourse under a Canadian plaza alike — the same thermal stability that makes an earth-sheltered home efficient makes an underground city livable.
Historic subterranean cities: Cappadocia and Beijing
The oldest examples are the most astonishing. In the Cappadocia region of central Turkey, soft volcanic tuff was excavated into multi-level underground cities — Derinkuyu being the deepest yet explored, descending roughly 60 meters (about 18 levels) with ventilation shafts, wells, stables, wineries, chapels, and heavy rolling stone doors. Successive cultures expanded these warrens over centuries, using them chiefly as refuges during invasions. They could reportedly shelter thousands of people along with their livestock.
In the twentieth century, defense drove Beijing's Dixia Cheng (“Underground City”), a vast network of tunnels and bunkers dug largely between 1969 and 1979 during the period of Sino-Soviet tension, intended to shelter and evacuate the population in the event of attack. Though much of it is now closed or repurposed, it stands as one of the largest deliberately built civil-defense undergrounds in history.
Why cities build down
Across every example, the drivers repeat in different proportions:
- Climate — escaping extreme heat (Coober Pedy, Cappadocia summers) or extreme cold (Montreal), using the ground's thermal stability.
- Land scarcity and connectivity — dense cities such as Montreal and Helsinki gain floor area and weatherproof pedestrian links without consuming surface land or blocking sunlight and views.
- Defense and civil protection — from Derinkuyu's invasion refuges to Beijing's Cold War tunnels to Helsinki's bedrock shelters, depth is the oldest form of hardening.
- Infrastructure that wants to be hidden — water treatment, parking, and heat-generating data centers do their jobs perfectly well underground, freeing the surface for people.
For the concepts that push this logic to its limit — including a proposed inverted-pyramid tower below Mexico City's central square — see our iconic projects guide, or read the buildable engineering in Building Down.
Sources and attribution: City of Montreal / RÉSO public information and the Place Ville Marie development history; City of Helsinki Underground Master Plan; District Council of Coober Pedy; published archaeology of Derinkuyu and the Cappadocia underground cities; public histories of Beijing's Dixia Cheng. Distances and figures are approximate and drawn from public sources.