Danube
The Danube was once a long-standing frontier of the Roman Empire, and today flows through 10 countries, more than any other river in the world. Originating in Germany, the Danube flows southeast for , passing through or bordering Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine before draining into the Black Sea. Its drainage basin extends into nine more countries. The Danube river basin is home to fish species such as pike, zander, huchen, Wels catfish, burbot and tench. It is also home to a large diversity of carp and sturgeon, as well as salmon and trout. A few species of euryhaline fish, such as European seabass, mullet, and eel, inhabit the Danube delta and the lower portion of the river.
Source of the Danube
The Donaubach spring was considered the source of the Danube since the 15th century at least (Hartmann Schedel in his Weltchronik from 1493), but several hints suggest that this might have been true even in Roman times (Pliny the Elder in Naturalis Historia), in which the river was located in the fringes of the populated areas. The oldest cartographic depiction by Sebastian Münster from 1538 shows the Donaubach spring as a rectangular pool; in 1875, the spring was modelled into a round pool after Adolf Weinbrenner's design. In 1895 the artist Adolf Heer created a group of statues above the pool, depicting “the mother Baar” showing her "daughter", the young Danube, the way. The supposed source of the Danube is a popular tourist attraction, which is however closed until Autumn 2015 due to extensive renovation and restoration.