List of tributaries of the Danube
The Danube is Europe's second-longest river. It starts in the Black Forest in Germany as two smaller rivers—the Brigach and the Breg—which join at Donaueschingen, and it is from here that it is known as the Danube, flowing generally eastwards for a distance of some , passing through several Central and Eastern European capitals, before emptying into the Black Sea via the Danube Delta in Romania.
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.