underground swimming poolItakeskus underground swimming complexPhoto: Lewis Martin

From the country that brought you the world’s spookiest children’s series, please meet the underground city. Helsinki, Finland’s capital, has decided to defeat sprawl by building down instead of out. Incised into the city’s bedrock are a swimming pool, a shopping area, a church, a hockey rink, and a data center, not to mention “parking caverns” and a bunch of the city’s necessary municipal doodads. An underground shadow city! Seriously, you guys, how is it possible for Finland to be so creepy and cool?

Some of the benefits here are obvious — it reduces outward city expansion and it makes use of the rock’s natural insulating properties. But some, like the data center, are even more innovative. Because the data center is underground (underneath a cathedral, in fact) and cooled by seawater, the heat from the computer banks can be channeled right into the city’s heating system. Instead of using up power for cooling, the computers save power for heating. Helsinki also stores its coal underground, out of eyesore-shot.

Helsinki is planning to expand the underground city in the near future:

With an increasing demand for sustainable development and sound planning of land-use within the area’s red and black granite, the City of Helsinki has decided to capitalise on future construction opportunities by formulating a strategic ‘Underground City Plan’.

This plan is being used to manage the construction of a further 200 underground structures in forthcoming years, including new metro lines and an ambitious road tunnel project, which will connect existing access roads leading into the city.