In the 20th century, important aircraft manufacturing facilities were situated in the city, such as the Arado Flugzeugwerke in Warnemünde and the Heinkel Works with facilities at various places, including their secondary "Heinkel-Süd" facility in Schwechat, Austria, as the original Heinkel firm's Rostock facilities had been renamed "Heinkel-Nord". The world's first airworthy jet plane prototype made its test flights at their facilities in what used to be named the "Rostock"- neighborhood (today's "Rostock"-"Schmarl" community, along the west bank of the Unterwarnow estuary).