The remains of the castle can be visited
Nonnenfels Castle

The Nonnenfels castle remains, also known as Nonnen-Fels, are the ruins of a medieval rock castle situated on a spur of the Schlamiesener Berg. Located west of Bad Dürkheim in the Palatinate Forest, it offers views over the Isenach Valley.
History+
There is no definitive knowledge regarding the exact period of construction or the builders of Nonnenfels Castle. Speculations range from an original wooden castle built between 1000 and 1200, to its establishment as an outwork for the nearby Hardenburg in the 13th century. The original name of the complex has also not been preserved. Precise dating is complicated by its later use as a quarry and by rockfalls. The circumstances of its destruction and abandonment are equally unclear, though destruction in the 17th century is presumed.
Image: http://www.wehrbauten.de/thread.php?threadid=1338
Location: 49.4655, 8.1187