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.
Danube
Before the last ice age in the Pleistocene, the Rhine started at the southwestern tip of the Black Forest, while the waters from the Alps that today feed the Rhine were carried east by the so-called "Urdonau" (original Danube). Parts of this ancient river's bed, which was much larger than today's Danube, can still be seen in (now waterless) canyons in today's landscape of the Swabian Alb. After the Upper Rhine valley had been eroded, most waters from the Alps changed their direction and began feeding the Rhine. Today's upper Danube is but a meek reflection of the ancient one.