The remains of the Castle can be visited
Gräfenstein Castle

Gräfenstein Castle Ruin, often known as Merzalber Schloss, is a rock castle in the Palatinate Forest. It is on a twelve-meter-high rock plateau and is considered one of the most significant Staufer-era castle complexes in Rhineland-Palatinate.
History+
The first documented mention of Gräfenstein dates back to 1237, in a partition deed of the Counts of Leiningen. The central complex with its keep and palas is dated to the 12th century, thus to the Staufer period. In 1317, the castle passed to the Leiningen-Dagsburg sideline, which, however, had to sell a large part to Elector Ruprecht I of the Palatinate by 1367. Through marriage, Gräfenstein came into the possession of the Counts of Leiningen-Hardenburg in 1421, who expanded the lower castle. After its destruction in the German Peasants' War in 1525, reconstruction began in 1535. In 1540, Count Palatine Ruprecht of Palatinate-Veldenz acquired the castle, made it his residence, and introduced the Reformation.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Graefenstein_kern.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 49.2409, 7.7568