This is Pionen White Mountains, the nuclear bunker in which Wikileaks will locate some of its servers. It was excavated 98 feet underground, in a rock hill in the center of Stockholm, Sweden, during the Cold War.
Originally, it was just a bomb shelter built in 1943. In the 70s, the Swedes turned the shelter into a full bunker, a civil defense center that was going to hold an emergency unit of the Swedish government in the case of a nuclear war.