This image is of the riverside town of Boppard.
Astudin-Karten vom Rhein. Verlag von Hausch & Bechstedt, Köln.
The description on the back translates roughly as follows:
Boppard. Town with 6500 inhabitants, is characterized by a particularly versatile environment and very scenic location on the river. In Boppard flow six lovely streams into the Rhine. It is the starting point of Hunsrückbahn [a now partially abandoned traction railway].
Population is now close to 16,000, 80+ years after this postcard was purchased.
This is number 127 in the series.