The largest river in Europe, the Danube, takes its sources from Germany and, after crossing 8 European countries, flows into the Black Sea. Virtuoso musicians from the countries along the Danube met onboard a ship. They sailed upstream in order to play the music springing from the native customs and traditions of their nations. In the language of music they managed to efface the boundaries, either actual or imaginary, which still exist in the minds of people.