With Kunstmuseum Basel's new building, a prominent location in inner-city Basel has been reclaimed. The extended museum comprises two directly interrelating buildings on opposite sides of the street.

The actual link between the main building and the new building beneath the street is not an underpass, but an extensive spatial structure that leads to a large hall at the bottom of the main steps. Each floor of the new building accommodates two exhibition wings that are vertically interconnected by the monumental flight of steps. Prefabricated sand-blasted concrete elements span the exhibition rooms as visible structural components, giving the ceilings a distinctive structure and giving the space a direction.

The new building's angular compact body is built as a solid construction. The structure reveals its load-bearing capacity via its spatial arrangement. The concrete walls of the exhibition spaces on the 1st and 2nd floors act as slabs and bridge the large halls on the ground floor. The ceilings on the ground floor and 1st floor are realised with sophisticated prefabricated ribbed ceiling elements. Left as raw exposed concrete, they hang from the ground floor's concrete walls and rest on the 1st floor's concrete walls. Funnel-shaped prefabricated skylight elements span the rooms on the 2nd floor.