Cottbus or Kottbus (both: kôtˈbŏs) [key], city (1994 pop. 128,120), Brandenburg, E Germany, on the Spree River. It is an industrial center and rail junction, but one that is heavily polluted with sulfur dioxide. Manufactures include textiles, leather, machinery, and building materials. Cottbus developed as a market center in the late 12th cent. and passed to Brandenburg in the mid-15th cent. It was annexed, with the rest of Lusatia, by Saxony in 1635 and was taken by Prussia in 1815.