In 1072, Archbishop Anno II of Cologne founded the Benedictine Abbey of Grafschaft. The abbey was intended to become the most important spiritual and economic center of the Sauerland region. Archbishop Anno II endowed the monastery generously. Mülheim was one of the 12 parishes and villages, as well as the tithes in kind from many other places, that the Benedictine monks received.
As early as 1266, a branch of the Teutonic Order was established here. The Teutonic Order’s commandery still consists today of the Teutonic Order Castle, the rent office building, and the chapel at the Sisters’ Cemetery.
Today, the impressive monastery complex is privately owned. The parish church and the Mariengrotte memorial are open to the public.