The Archbishop of Cologne Anno II founded the Benedictine Abbey Grafschaft in 1072. The building was intended to create the most important spiritual and economic center of the Sauerland. Archbishop Anno II richly endowed the monastery. Mülheim belonged to the 12 parishes and villages and the natural tithes of many other places, which the Benedictine monks received.
As early as in 1266 a branch of the Teutonic Order was established in this place. The Teutonic Order commune still consists of the Teutonic Order castle, the retreat building and the chapel in the sisters' cemetery.
Today, the impressive monastery complex is privately owned. The parish church and the Mariengrotte memorial are open to the public.