The remains of the castle can be visited
Linau Castle

The Linau Castle remains in Schleswig-Holstein are located in the municipality of Linau in the Duchy of Lauenburg.
History+
First mentioned in 1230, Linau Castle was built at the end of the 13th century by the robber knights of Scharpenberg. Its location allowed for the monitoring of trade traffic, leading to repeated conflicts. As early as 1291, Wendish princes, cities, and the Dukes of Lauenburg allied against the Scharpenbergs to destroy the castle. Although its demolition was agreed upon, the robber knights rebuilt the complex. An attack by Count Gerhard II in 1312 with trebuchets also proved unsuccessful. Count Johann the Mild built Trittau Castle in 1326 for defense, but the Scharpenbergs' raids continued. Another attack by Hamburgers and Lübeckers in 1338 also failed. It was not until 1344 that the Lauenburg Dukes Erich the Elder and the Younger bought the castle from the Scharpenbergs to break their power. However, the Scharpenbergs later recaptured the castle.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:RK_0704_00487_Burg_Linau.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: 53.6459, 10.4680