Photos

The Danube is the longest river in the European Union and Europe's second longest river after the Volga.

The river originates in the Black Forest in Germany as the much smaller Brigach and Breg rivers which join at the eponymously named German town Donaueschingen, after which it is known as the Danube and flows eastwards for a distance of some 2850 km (1771 miles), passing through four Central and Eastern European capitals, before emptying into the Black Sea via the Danube Delta in Romania and Ukraine.

Known to history as one of the long-standing frontiers of the Roman Empire, the river flows through — or forms a part of the borders of — ten countries: Germany (7.5%), Austria (10.3%), Slovakia (5.8%), Hungary (11.7%), Croatia (4.5%), Serbia (10.3%), Romania (28.9%), Bulgaria (5.2%), Moldova (1.7%), and Ukraine (3.8%).