The river Danube is the second longest river in Europe after the Volga. This river rises on the Black Forest mountains of western Germany and ends on the Black Sea; it passes trhough ten countries: Germany, Austria, Slovakia, Hungary, Croacia, Serbia, Bulgaria, Romania, Moldova and Ukraine. Danube measures 2850 kilometres. Its waters served as a vital comercial highway between nations. Also, the river’s majesty has been celebrated in music, for example, the famous waltz An der schönen, blauen Donau by Johann Strauss the Younger.
PICTURES:

File:Panorama of Danube in Vienna.jpg. (2019, January 13). Wikimedia Commons, the free media repository. Retrieved 08:34, Maty 23, 2019 from https://commons.wikimedia.org/w/index.php?title=File:Panorama_of_Danube_in_Vienna.jpg&oldid=334685946.
File:Danubemap.png. (2015, January 15). Wikimedia Commons, the free media repository. Retrieved 08:35, May 23, 2019 from https://commons.wikimedia.org/w/index.php?title=File:Danubemap.png&oldid=146588937.
Danube River, Enciclopedia Britanicca, Inc., Patricia Garland Pinka and Peter Georgiev Penčev, May 23, 2019, from https://www.britannica.com/place/Danube-River.