Wikipedia
Marksburg
The Marksburg is a castle above the town of Braubach in Rhineland-Palatinate, Germany. It is one of the principal sites of the Rhine Gorge UNESCO World Heritage Site. The fortress was used for protection rather than as a residence for royal families. It has a striking example of a bergfried designed as a butter-churn tower. Of the 40 hill castles between Bingen am Rhein and Koblenz the Marksburg was the only one which was never destroyed.