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 Banovina
The Danube Banovina or Danube Banate ( / Дунавска бановина), was a banovina of the Kingdom of Yugoslavia between 1929 and 1941. This province consisted of the geographical regions of Srem, Bačka, Banat, Baranja, Šumadija, and Braničevo. The capital city of the Danube Banovina was Novi Sad. The province was named after the Danube River.