The state of NRW provided the founding director of the NRW Art Collection, Werner Schmalenbach, with the highest German acquisition budget at the time. The art collection, which is entirely state-owned, was shaped by Schmalenbach with high expertise and absolute instinct and contains masterpieces by, among others, Picasso, Matisse, Kandinsky, Kirchner, and Mondrian, American art after 1945 with Warhol, Rauschenberg, or Pollock, as well as works by Georg Baselitz and Gerhard Richter. Under his successor Armin Zweite, a representative collection of Joseph Beuys was also acquired.
In addition, after renovation and repurposing of the former Ständehaus at Kaiserteich, the former parliament of the Rhine Province, the K21 was added as a branch. Only the exterior facade of the Ständehaus has been preserved; inside, all fixtures were removed except for the historical staircase. The roof was also taken off and replaced with a spectacular glass dome, which is used as an additional exhibition space. In K21, parallel to a program of changing exhibitions as in K20, essential positions after the postmodern turn have been represented since spring 2002: about 170 works, including Bernd and Hilla Becher and the Düsseldorf Photo School, Marcel Broodthaers, Nam June Paik, Thomas Schütte, and Jeff Wall.
