The former nuclear shelter that is converted into a stylish office for Bahnhofs. The entrance is at Renstiernas gata 37. Photos can be seen at the website of Albert France Lanord Architecture, the architect who designed this office. According to Bahnhofs's website, you can visit the site by emailing them at firstname.lastname@example.org.
HT: H.O.M.E. magazine, July/August 2010.