Countries: Germany, Austria, Slovakia, Hungary, Moldova, Serbia, Romania, Bulgaria, Croatia, Ukraine Cities: Ulm, Ingolstadt, Regensburg, Passau, Vienna, Bratislava, Budapest, Mohács, Vukovar, Ilok, Novi Sad, Belgrade, Drobeta Turnu-Severin, Vidin, Rousse, Galaţi Primary source: Breg – location: Martinskapelle, Black Forest, Germany – elevation: 1,078 m (3,537 ft) – length: 49 km (30 mi) – coordinates: 48°05′44″N 08°09′18″E [...]