Eisenach (Īˈzənäkh) [key], city (1994 pop. 42,580), Thuringia, central Germany. It is an industrial center and rail junction. Industries include tourism, the manufacture of machinery, metal and wood products, chemicals, and electrical goods. The well-known Wartburg automobile factory was forced to close in 1991 due to economic hardship following German reunification, but a new Opel automobile plant opened the following year. There are salt mines and saline springs in the region. Eisenach was founded c.1150 and was chartered in 1283. The city passed to the house of Wettin in 1440, to the Ernestine branch of the Wettin dynasty in 1485, and to Saxe-Weimar (later Saxe-Weimar–Eisenach) in 1741. It often served as a residence of the electors of Saxony and the dukes of Saxe-Weimar. The German Social Democratic party was founded there (1869) at the Congress of Eisenach. The city's noteworthy buildings include the Church of St. Nicholas (12th cent.) and an 18th-century castle. Nearby is the famous Wartburg castle. Johann Sebastian Bach was born (1685) in Eisenach and Martin Luther studied there (1498–1501), beginning his translation of the Bible in the Wartburg.