In 15 BC Tiberius Claudius Nero (42 BC-37 AD), Roman Emperor (14-37 AD), led the campaign through the Upper Rhine Valley to the Lake Constance to force the Celts into subjugation. When the conquering Romans advanced further to the north, they discovered the headwaters of the Danube River in the modern-day Germany.
The headwaters of the Danube River are situated in the Swabian Jura in a so-called Karst-Area, a unique landscape that results from the weathering of bedrock types that are soluble in water. These bedrock sediments are primarily limestone. Rainwater slowly infiltrates cracks in the limestone, dissolving the rock and enlarging the underlain openings and underlain caves. Millennia of water flowing through these landforms create unique and sensitive ecosystems.
The question of where to find the genuine source of the Danube River has kept scholars busy for centuries. Is it in Donaueschingen, in St. Georgen or in Furtwangen? The fact is that all three towns are situated in the Black Forest, in the district of Schwarzwald-Baar, in Baden-Württemberg, one of the 16 federal states, in the south-western Germany. Today this question has definitively been settled. The Danube River begins at the confluence of the two headstreams: Breg and Brigach near Donaueschingen, in the Black Forest. It is almost at the border with Switzerland, and an area that is a known habitat and spices protection area.
In 1538 the Cosmographer Sebastian Münster (1488-1552), one of the most eminent German humanists and all-round scholars, marked the source of the Danube River with a quadrangle on a map and inscribed it with “fons danubii” (Lat.: the source of the Danube). Furthermore, he described the Donaubach as “Danuvius” and explained how Donaubach and Brigach come to form the Danube River. Therefore the extent of the Danube River started at the confluence of these rivers in this time period.