The volume of the new extension starts from the constrains given by property boundaries and the neighboring existing buildings. To harmonize this fragmented situation the new building is characterized by light joints, which connect the opposite courtyards. The result is a range of six constructs shifted between each other to enhance and optimize the exposure to natural light. The new building is laterally bordered by the historical Bundesrat to the east and the Leipzig Plaza buildings in the west. The north facade of the new extension is compressed by the strong identity of the adjacent buildings .
To connect the different architectural languages of the neighboring building, the design propose a monolithic stone façade. The new extension receives then enough weight to stand out as a separate building but at the same time it pay respect especially to the historical Bundesrat. A small gap in the upper part of the monolithic façade is aligned with the decoration of the historical building to symbolizes affiliation. In the ground level, the facade set back and forms an extension of the loggia of Strasse 11.