The core principle of the planning was founded on the retention of original materials at all levels of historic and cultural value. The value of Stüler’s original building was recognised as of paramount importance. In addition to this there are levels of importance, which tell of substantial architectural alterations – initially through new museological ideas, later through the tragedy of bombardment during the war and the subsequent dereliction of the ruin during the following decades. The restoration planning devotes particular attention to the variability of the state of conservation. The range of conditions stretches from almost completely preserved rooms to room sequences, whose surfaces are partly destroyed due to weathering, to the exposure of Stüler’s shell construction and the loss of whole building elements. The restoration design was developed individually for each room and reviewed in context of the room sequence. In some instances the damaged building offers an obvious design solution to a question of architectural completeness or resolution. In others, the damaged condition is of such significance, that within a context of careful debate, a balance had to be devised between the methods - from repair to conservation culminating in restoration.