There's the so-called "Lochmühle" (Hole Mill) an old water mill and nowadays a restaurant located at the Blau River in Ulm, Baden-Württemberg, Germany.
In 1356 the mill is mentioned for the first time in a letter. However, the mill must have existed for a long time before 1356.
The south gable of the mill is still in the original state and the "Lochmühle" is the oldest preserved mill in Ulm. In 1977 it was renovated and altered to an restaurant. The water wheel of the mill is still working.