The remains of the Castle can be visited
Fürstenberg Castle

The castle ruin of Fürstenberg, a former hilltop castle, is part of the UNESCO World Heritage Upper Middle Rhine Valley and is located in Oberdiebach in the Mainz-Bingen district of Rhineland-Palatinate.
History+
The origins of Fürstenberg Castle date back to 1219, when it was built on behalf of Archbishop Engelbert of Berg to secure the possessions of the Electorate of Cologne around Bacharach. As early as 1243, the castle passed as a fief to the Electors Palatine, who finally acquired it in 1410. In the 15th century, the complex was reinforced by the addition of a tower to the curtain wall to allow for better defense with firearms.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=899&sid=246e8c9fdbfa80ccf9a3497b2adfd6ed
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: 50.0417, 7.7874