Tula (tōˈlə) [key], city (1991 pop. 545,000), capital of Tula region, N central European Russia, on the Upa River, a tributary of the Oka. It is an important rail and highway hub and a manufacturing city of the Moscow industrial region. Russia's oldest metallurgical center, it also produces heavy and light machine tools. Lignite is mined nearby and is used to support a chemical industry. First mentioned in 1146, Tula was included in the Ryazan principality. In the 16th cent., the city became a key fortress of the grand duchy of Moscow. Peter I built Russia's first arms factory at Tula in 1712, based on the discovery nearby of iron and coal deposits. Tula subsequently became a center of the Russian ironworking industry. Serving as the southern anchor of the Moscow defense line during World War II, the city withstood heavy German assaults. The 16th-century kremlin, with turreted walls, has been preserved. Yasnaya Polyana, the home and burial place of Leo Tolstoy, is nearby.