Knippers Helbig has created the structural design for a hotel and apartment house complex in the Voltairestraße in Berlin located in close proximity to the Alexanderplatz. The complex consists of multiple building structures, surmounted by a tower with a height of 60m. The individual parts of the building have two common basements, which are primarily intended for underground garage facilities. The main structure is designed as a reinforced concrete frame structure with multiple stiffening cores. The core walls are clamped on a rigid cellar box system in the basements. Through the static optimisation of the slab thickness and support cross-sections, it was possible to optimise the building height and floor area with a very positive impact on the overall cost effective-ness.