Two real springs are actually referred to as the source of the Danube - symbolically that of the Donaubach in Donaueschingen and hydrologically that of the larger source river Breg at the Martinskapelle near Furtwangen.
Today, the confluence of the rivers Breg and Brigach is regarded as the beginning of the Danube by name.
For centuries, scholars argued about the source and main source of the Danube, until the following definition was recorded in the books: The water of rivers gathers from an almost unmanageable number of source channels that gradually merge.
The main course of such a river system is formed at the many points of union by the larger river upstream, and thus also the source of the entire river. Accordingly, the actual source of the Danube is the Breg in Furtwangen!