The remains of the castle can be visited
Heidenschuh Castle

The Heidenschuh castle ruin, a hilltop castle, is on the Treitelsberg near Klingenmünster in Rhineland-Palatinate. It is a section fortification, blocking off a steep-sided mountain spur.
History+
The Heidenschuh served as a refuge castle for the inhabitants of Klingenmünster Monastery and the surrounding villages. Its origin is presumed to be in the Early Middle Ages, possibly during the Carolingian-Ottonian period of the 8th to 9th centuries. Historical documents concerning the fortification have not been preserved, and the original name of the complex is unknown. The current name “Heidenschuh” only became established in the 18th century, when the ruin was attributed to heathens.
Image: http://www.wehrbauten.de/thread.php?threadid=1456
Location: 49.1553, 7.9987