A behavior like "cat and mouse" is not just a saying: The disputes of castle lords from earlier years also manifested in their construction activities.
Thus, the castle known as Deuernburg, "Mouse," is ultimately a counter-castle to the castle "Cat" in the conflict of the Counts of Katzenelnbogen with Electoral Trier. The castle "Mouse" was established in 1356 by the Archbishop of Trier, Boemund II, in St. Goarshausen-Wellmich - and was oriented from the very beginning against the upstream Rheinfels, a castle of the aforementioned Counts of Katzenelnbogen. These counts did not take long to counter the threat to their customs clearance in St. Goar posed by the new Deuernburg on the opposite bank of the Rhine, and completed their castle Neu-Katzenelnbogen - later called castle "Cat" - as an unfriendly response before 1371. Together, the two fortifications are among the most famous attractions in the Rhine Valley. In contrast to the "enemy castle Cat," the "Mouse," with its core structure rebuilt from 1900 onwards, provides an impression of medieval castle architecture.

The castle is privately owned and is currently only viewable from the outside.