Arnstadt (ärn`shtät), city (1994 pop. 27,470), Thuringia, E Germany, on the Gera River. Known for its glove-manufacturing industries, Arnstadt also has glassworks, wood-finishing works, and foundries. Fluorspar and manganese are mined nearby. Arnstadt passed to the counts of Schwarzburg in the 14th cent. and later was the capital of the principality of Schwarzburg-Sonderhausen. Noteworthy buildings include the 13th-century Church of Our Lady and an 18th-century palace. J. S. Bach was organist (1703–5, 1706–7) at the Church of St. Boniface there.