Winterthur (vĭnˈtərtōrˌ) [key], city (1990 est. pop. 85,200), Zürich canton, N Switzerland. An industrial center, it is an important rail junction and has manufactures of railroad equipment (including locomotives and diesel engines) and cotton textiles. It is also a cultural center with an old music festival and two excellent art collections. Winterthur was ruled by the counts of Kyburg (whose castle stands south of the city) until 1264, when it passed to the Hapsburgs. It became a free city of the Holy Roman Empire in 1415 and in 1467 was bought by Zürich.