Pionen is a former civil defence centre constructed in the White Mountains Södermalm borough of Stockholm, Sweden in 1943 to safeguard essential government functions. It was transformed into a data centre by the Swedish internet service provider, Bahnhof.
Sweden’s Bahnhof Data Centre was officially opened on September 11, 2008, and the company continues to use the facility till now. The building is concealed under the mountain and is secured by a 15.75 in (40 cm) thick door and can only be reached by an entrance tunnel. Due to all of these features, the data centre can withstand even a hydrogen bomb.
