Danube
Classified as an international waterway, it originates in the town of Donaueschingen, in the Black Forest of Germany, at the confluence of the rivers Brigach and Breg. The Danube then flows southeast for about , passing through four capital cities (Vienna, Bratislava, Budapest and Belgrade) before emptying into the Black Sea via the Danube Delta in Romania and Ukraine.
Donau City
Unlike in many other cities, the Danube River, because of the numerous floods it regularly caused, was omitted from the urban area. Buildings grew up in Vienna on both sides of the Danube - but not up to the Danube. Only after extensive flood-control engineering and the creation of the New Danube relief channel, with Danube Island, in the 1970s, was the surrounding cityscape of the Danube of interest to builders.