Danube
The Danube flows through many cities, including four national capitals (shown below in bold), more than any other river in the world. Ordered from the source to the mouth they are:
The Danube is navigable by ocean ships from the Black Sea to Brăila in Romania and by river ships to Kelheim, Bavaria, Germany; smaller craft can navigate further upstream to Ulm, Württemberg, Germany. About 60 of its tributaries are also navigable.
Danube–Black Sea Canal
For much of the 1950s, the Danube – Black Sea Canal was celebrated in agitprop literature (notably, in Geo Bogza's 1950 reportage "Începutul epopeii", "The Beginning of the Epic", and in Petru Dumitriu's "Drum fără pulbere", "Dustless Road"), music (Leon Klepper's symphonic poem "Dunărea se varsă în mare", "The Danube Flows to the Sea"), and film (Ion Bostan's 1951 "Canalul Dunăre-Marea Neagră, o construcție a păcii" – "The Danube – Black Sea Canal, a Construction of Peace"). During the 1980s, the song "Magistrala Albastră" (The blue freeway), performed by Dan Spătaru and Mirabela Dauer and using the Canal as its setting, was frequently broadcast in official and semi-official contexts.