Danube-Auen National Park on both land and water, and other invertebrates, the total number of species in Donau-Auen National Park is estimated to be at least 5,000. Danube-Auen National Park Donau-Auen National Park () covers 93 square kilometres in Vienna and Lower Austria and is one of the largest remaining floodplains of the Danube in Middle Europe. The German word Aue (variant Au) means "river island, wetland, floodplain, riparian woodland", i.e. a cultivated landscape in a riparian zone. The words Aue and Au occur in a large number of German place names—including Donau, the German word for the Danube River—and refer to forests,
The Blue Danube The Blue Danube "The Blue Danube" is the common English title of "", Op. 314 (German for "By the Beautiful Blue Danube"), a waltz by the Austrian composer Johann Strauss II, composed in 1866. Originally performed on 15 February 1867 at a concert of the (Vienna Men's Choral Association), it has been one of the most consistently popular pieces of music in the classical repertoire. Its initial performance was considered only a mild success, however, and Strauss is reputed to have said, "The devil take the waltz, my only regret is for the coda—I wish that had been a success!"