Fürstenburg Castle in Rheindiebach, was founded in 1219 by the Archbishop of Cologne, Engelbert I. With its construction, the Archbishops of Cologne attempted to restrict the growing influence of the Rhenish count palatines who, however, soon obtained signeurship. In 1314, the imposing building changed liege lords for the second time: the king of the Holy Roman Empire pledged it to the Electorate of Mainz. The front tower castle was thus under the sovereignty of three different electorates in the course of one century. After severe damage during the Palatine War of Succession, it remained in a state of ruins. Changing owners, among them the current owner, have always cultivated the surrounding vineyard. Hikers can reach the ruin through a detour from the nearby RheinBurgeWeg trail.