In June 2002 good friends of ours bought a three storey World War II Bunker in the middle of their favourite quarter of Bremen, Germany, in order to convert and extend it into a house for themselves and their two children. Their idea was to build a two-storey ‘penthouse’ on top using this massive structure as a plinth for their new home. A strategy emerged in which part of the house occupies part of the existing structure -like an inlay, insulated from inside, ‘eating’ its way through to the surface and the light - and connects through the roof with the ‘penthouse’ space built on top. A compact three-storey house plugged into another three-storey structure describes the basic configuration.