The Danube is second only to the Volga River in Europe and the second longest river in Europe. It originated in southern Germany, flowing from west to east, flowing through Austria, Hungary, Ukraine and other places, and then injected into the Black Sea. The blue Danube slowly passes through the city of Vienna, and by boat, the riverside scenery is very good, with ancient Gothic architecture. The beautiful Viennese forest stretches out in the western suburbs of the city and is lush. Every summer, there is a colorful music festival.