Chateau Graaf is a moated castle, picturesquely situated in Wallonia. The oldest part of the castle dates back to the Carolingian period. The castle is owned by a private owners’ association. Together with castle owner, inventor and designer Günther Kunz, we share an enthusiasm for traditional greenhouse architecture, garden city concepts and the famous glass house by architect Bruno Taut (Werkbundausstellung 1914, Cologne). Kunz succeeded in deciphering the geometric formation principle of Taut’s glass house and is now able to construct and vary the rhombohedral design. We realised the world’s first built variation of this dome as an experimental building in the castle park of Chateau Graaf. Like a crystal, it rises above the garden studio from the surrounding landscape. The statics, calculated by Prof. W. Führer of the Institute for Structural Engineering at the RWTH Aachen, form a flower pattern. The domed house was opened by Susanne Kiefer-Taut, the granddaughter of Bruno Taut, at the exhibition “Phasenübergänge – es brennt es schmilzt es TAUT“, which took place on the occasion of the great castle fire in 2005.