The extension to Staedel Museum is placed along the central axis reinstating the historic spatial arrangement. The central foyer and all vertical access are remodeled in order to make the whole building wheelchair accessible. The spaces for special exhibitions are located on the ground floor linked directly with the foyer and the new extension. Administration, the Metzler auditorium and the library are relocated to the west wing. The new space below the garden houses the 20th century art collection. This space is dominated by a gently domed, airy ceiling with circular roof lights. The domed ceiling is a prominent feature in the topography of the garden above and resembles a land art object. Due to its compact underground building volume, the type of heating and cooling and the large heat storage capacity create an optimal room climate with minimal energy consumption.