Hagen rewards visitors with a serious interest in modern art or industrial heritage. Karl Ernst Osthaus's early 20th-century campaign to make this Ruhr-edge town a centre of Jugendstil left behind two extraordinary buildings — the Osthaus Museum and the Hohenhof villa — both still important reference points in the history of modernism. The LWL Open-Air Museum, in a wooded valley on the eastern edge of the city, is one of the largest of its kind in Germany.