The expansion of the Marie-Elisabeth-Lüders-Haus, the office building of the German parliament in Berlin, presented a number of challenges for the structural engineers. The central hall of the building was constructed over an existing supply tunnel that was not designed for an increase in load. Consequently, the structural loads on both sides of the existing tunnel had to be transferred in a controlled manner into the foundations of the existing part of the building and into the newly constructed foundations. This required a sophisticated measurement and monitoring program to control the forces and deformations during construction. The new building foundations consist of a combined pile and raft foundation to minimize settlement in the adjoining existing building. The structure was planned as a monolithic reinforced concrete structure with high demands on the exposed concrete.