Essen (ĕsˈən) [key], city (1994 pop. 622,380), North Rhine–Westphalia, W Germany, on the Ruhr River. The major industrial center of the Ruhr district, it was the seat of the famous Krupp steelworks. Essen is a retail trade center, a rail junction, and a steel and electricity producer. Its diversified industrial base includes chemical, glass, textile, and precision-instrument plants. The region's last coal mine closed in 1986 and in recent years there has a move away from heavy industry into the service and technology sectors. Essen grew up around a Benedictine convent (founded in the mid-9th cent.). It was a small imperial state, ruled by the abbess of the convent, from the 13th cent. until 1802, when it passed to Prussia. The city's main industrial growth dates from the second half of the 19th cent. Essen was heavily bombed during World War II, but was rebuilt in modern style after 1945. The city has a number of large parks. There is a noteworthy cathedral (9th–14th cent.).