Ostrava (ôˈsträvä) [key], formerly Moravská Ostrava môˈräfskä, Ger. Mährisch Ostrau, city (1991 pop. 327,371), NE Czech Republic, in Moravia, near the junction of the Oder and Ostravice rivers. It is the heart of the Ostrava-Karviná industrial and mining region, the most heavily industrialized area of the Czech Republic. Coal, important to the city for some 200 years and the reason it was nicknamed "black Ostrava," is no longer mined; the city's major industries now include metallurgy, engineering, and information technology. One of the Czech Republic's largest cities, Ostrava is a regional administrative center, a road and rail hub, and the site of several hydroelectric stations.
Ostrava was well known as a small town in the Middle Ages and later became important because of its strategic location guarding the Moravian Gate, the entrance to the Moravian lowlands. The city's industrial prominence dates from the late 19th cent., after the opening of its first coal mine and the coming of the railroad. The modern city was created in 1924 by the merger of seven towns. German forces occupied Ostrava from 1939 to 1945. The city is a cultural and educational center, noted especially for its technical university and mining museum. The St. Wenceslas church (14th cent.) is Ostrava's oldest building; the Cathedral of the Divine Savior was completed in 1889.