Windisch (vĭnˈdĭsh) [key], town, Aargau canton, N Switzerland, on the Reuss River near its confluence with the Aare. Textiles and cables are made there. Originally a Helvetian settlement, it later became a Roman camp called Vindonissa. A Roman amphitheater, which accommodated over 10,000 spectators, has been excavated. Nearby are the remains of the once powerful monastery of Königsfelden, erected in 1310 on the site where Holy Roman Emperor Albert I had been murdered. The monastery church is a splendid example of Swiss Gothic architecture, with fine stained glass.