city, Thuringia Land (state), central Germany. It lies on the northwestern slopes of the Thuringian Forest, at the confluence of the Hörsel and Nesse rivers, west of the city of Erfurt. Founded by the landgraves of Thuringia about 1150, Eisenach fell to the Saxon house of Wettin in 1264 and was chartered in 1283. It was intermittently the seat of a separate Saxon duchy between 1596 and 1741, when it fell to Saxe-Weimar. In 1817 the festival of the national political student movement took place there. The German Nationalverein (National Society) to promote unification was founded in Eisenach in 1859, and in 1869 the Social Democratic Workers' Party was founded at the Congress of Eisenach.

Tourism thrives, and industries include the manufacture of motor vehicles, machinery, metal and wood products, chemicals, and electrotechnical goods. Eisenach is a centre of the important Werra potash field. Notable landmarks include the Romanesque Church of St. Nicholas; the Gothic St. George's Church; the Thuringian Museum in the former ducal palace (1742–45); the 13th-century Dominican Church; the Lutherhaus, where Martin Luther (Luther, Martin) stayed as a schoolboy; museums in memory of the composers Johann S. Bach (Bach, Johann Sebastian) (born at Eisenach in 1685) and Richard Wagner (Wagner, Richard) and the novelist Fritz Reuter (Reuter, Fritz); and a botanical garden. On a hill above the city is the Wartburg, an ancient castle of the landgraves, where Luther began his translation of the Bible; the castle was designated a UNESCO World Heritage site in 1999. Pop. (2003 est.) 44,081.