K21 is housed in the former parliament building of North Rhine-Westphalia and focuses on contemporary art from 1980 onwards. The building features a stunning glass dome designed by Kiessler with the interactive artwork 'in orbit' by Tomás Saraceno that visitors can walk on. The collection includes works by artists such as Beuys, Kiefer and Gursky. The historic building itself with its ornate corridors is worth visiting.