Aach- beautiful old city with a castle on the top

The water of the Aach source comes mostly from the Danube, which seeped between Immendingen and Fridingen and created by the porous karst rock an underground drain.
 By the way, it is interesting to imagine that at the sinking sites it is decided whether the water flows with the Danube river towards the Black Sea or the North Sea.
The mouths of the Danube and Rhine are at least about 1800 km apart.

The largest source in the country.

The place which is marked is a nice restaurant directly in the river Aach