In 1966 Mülheim was the first city in the Ruhr Area to become completely free of coal mines, when its last coal mine "Rosenblumendelle" was closed.
Mülheim an der Ruhr merupakan kota pertama di wilayah Ruhr yang bebas sepenuhnya dari pertambangan batu bara, ketika pertambangan terakhirnya "Rosenblumendelle" ditutup.