Opava (ôˈpävä) [key], Ger. Troppau, city (1991 pop. 62,815), NE Czech Republic, in Moravia, on the Opava River and near the Polish border. A prosperous market center in a fertile agricultural region, it has food-processing plants and industries producing clothing, machinery, and railroad cars. The city is also a road and rail hub. Opava was founded in the 12th cent. and later became the capital of Austrian Silesia. In 1820 representatives of the European great powers met there, at the Congress of Troppau, to discuss problems arising after the settlement of the Napoleonic Wars. City landmarks include a 15th-century cathedral built by the Teutonic Knights, the 15th-century Church of St. George, and a 17th-century Jesuit foundation.