Danube to Budapest Author:Martin Gostelow From its source in south-west Germany, coursing through central Europe and the Balkans, the Danube is a river of romance, passing medieval castles, baroque churches and rococo palaces. Europe's second-longest river, it flows through proud cities - Vienna, Budapest, Bratislava - forming the frontier between Romania and Bulgaria before branching i... more »nto a delta and pouring into the Black Sea. "This Way the Danube" sails along the navigable stretch of the river between Passau and Mohacs, near the Hungarian border with Croatia.« less