Which river flows through both Vienna and Budapest?

The Danube flows through both Vienna and Budapest.

The Danube is Europe’s second-longest river, running generally eastward from the Black Forest in Germany to the Black Sea. Along its route it passes through or borders more countries than any other river in the world, making it a major geographic link between central and southeastern Europe.

Vienna, Austria, and Budapest, Hungary, are two of the river’s best-known capital cities. Bratislava and Belgrade also stand on the Danube, so the river is associated with four national capitals in total. Its basin includes parts of many additional countries.

The river has supported trade, farming, fishing and settlement for thousands of years. Johann Strauss II’s 1866 waltz “The Blue Danube” helped make its name famous, although the river often appears greenish, brownish or grey rather than blue. The Danube Delta, where it reaches the Black Sea, is one of Europe’s most important wetlands.