The exposed site of the transformer-building GW 106, turning AC to DC for the streetcar-line, did not allow the standard type of construction usually provided for this function. So a selected design competition was performed in 2004. A special focus was put on the roof and landscape, which would both be seen from the elevated railwayline. The solution is a threedimensional shell, multiple-folded, beginning as a streetfacade, turning into a roof and across the back elevation into the surface of the open space behind the building. The function itself is positioned under this shell, materialized in metal-panelling in the corporate yellow colour of the BVG. The two-layer concrete construction with core insulation has differently treated surfaces, adequate to the way they are exposed: turning from very smooth along the street to more and more rough at the landscape-side, achieved through different intensity of sandblasting. Expectable weathering is part of the design and will change the appearance every year. The letters in braille writing along the pavement – meaning “ULAP” – give a note on the history of the site: the “Universum Landes-Ausstellungs-Park”, an exhibition place that was established here in the late 19th century and also gives a name to the park south of the railwayline.