MULHEIM AN DER RUHR

city, North RhineWestphalia Land (state), western Germany, just southwest of Essen, in the Ruhr industrial region. First mentioned in 1093, it was early associated with the counts von Broich, whose medieval castle still overlooks the city. It later belonged to the duchy of Berg, with which it passed to Prussia in 1814. It was chartered in 1808. Between 1878 and 1929 Mlheim absorbed a number of neighbouring towns, including Broich and Heissen. Historical buildings include St. Peter's Church (11th century, now entirely rebuilt); Styrum Castle and the former Cistercian convent of Saarn (both 13th century); and the house of Gerhard Tersteegen (d. 1769), a pious braid maker and hymn writer. Mlheim is a hub of rail and road traffic and a Rhine-Ruhr river port. Well-planned modern sections were reconstructed after World War II, and there are many open-air recreational facilities, including the Raffelberg racecourse and spa. Heavy industry includes iron foundries, blast furnaces, tube and rolling mills, and machine works. There are also chemical and electrical industries. Mlheim was formerly an important coal-mining centre. Located in the city is the Max Planck Institute for Coal Research, where the Fischer-Tropsch process for liquefying coal and the Ziegler process for the production of polyethylene plastics were discovered. Pop. (1989 est.) 175,454.