The Swedish datacentre with a bunker mentality

"We get in through a long tunnel from the street, protected by blast doors," Bahnhof chief executive Jon Karlung told ZDNet UK.

The tunnel surfaces at 37 Renstiernas Street in Stockholm. It was begun in 1943 and extended during the Cold War to became a civil-defence bunker, stocked with provisions and emergency vehicles. Key staff could survive a nuclear war there, and emerge to rebuild the city.

"The cave was owned by the fire department," Albert France-Lanord, the architect behind the bunker's conversion to a datacentre, told ZDNet UK. "In the '90s, it was used for raves, galleries and an 'underground' theatre scene."

The datacentre is called 'Pionen' ('Peonies' in English), its code name from when it was part of Stockholm's civil-defence system.