K21 features international art from 1980. With large and important works by Marcel Broodthaers und Nam June Paik, it sums up specific points of origin in the 60s and 70s. The first works of contemporary art were acquired during the foundation and opening phase of the new building. These essentially include photographic works by Andreas Gursky, Candida Höfer, Thomas Ruff, Thomas Struth and Jeff Wall, but also a video installation by Eija-Liisa Athila and a sculptural work by Thomas Schütte. In July 2004 the young museum was considerably enlarged, and in a tailor-made fashion, with the acquisition of the Ackermans collection by the region of North Rhine-Westphalia.
Having been assembled since the 80s, the collection now juxtaposes works which give outstanding visual form significant aspects of art since the beginnings of postmodernism. And in its concentration on sculpture and object art on the one hand, and photography on the other, the collection clearly demonstrates the close connection between German and international art during this period. There are well over 100 works, some of them in large formats. At the centre of the collection are works which show a reawakened interest in figuration, narrative, metaphor and a fascination with powerful images.
The cornerstones of the collection are artists like Katharina Fritsch, Robert Gober, Paul Mc Carthy, Reinhard Mucha, Thomas Ruff, Thomas Schütte, Jeff Wall and Franz West, each of whom are represented by several works or sets of works. Other outstanding works are by artists such as Christian Boltanski, Tony Cragg, Richard Deacon, Thomas Demand, Fischli & Weiss, Georg Herold, Thomas Hirschhorn, Ilya Kabakov, Juan Muñoz, Tony Oursler, Bill Viola and Rachel Whiteread. With a group of works from the sphere of Arte Povera (Jannis Kounellis, Mario Merz, Michelangelo Pistoletto) a connection is clearly established – as in the works by Broodthaers and Paik – with earlier artistic trends, and hence with the programme of K20.