After the completion of the Oberkassel/Ramersdorfer basalt quarrying in the 19th century, some of the up to 70 sMeter deep quarrying sites filled with groundwater. Embedded in cliffs, the Dornheckensee …
Nice hiking trail along some ponds in the nature reserve. Quite crowded at the weekend, as it is one of the most popular routes for the people of Rheinbach.