The Fortress can be visited
Königstein Fortress

Königstein Fortress, one of Europe's largest mountain fortresses, crowns a mesa in the Elbe Sandstone Mountains. Situated on the eponymous table mountain, it presents a sight above the town of Königstein on the left bank of the Elbe River.
History+
The first documented mention of a castle on Königstein dates back to 1233 in a document by King Wenceslaus I of Bohemia. The medieval complex belonged to the Bohemian Kingdom and was first fully referred to as “Königstein” in 1241. It served as an outpost and was conquered by the Meissen margraves in 1408 during the Dohna Feud. The transfer to the Margraviate of Meissen was finally sealed in 1459 with the Treaty of Eger. Königstein was continuously used and expanded militarily by the Saxon dukes and electors.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Mobile Geschichte
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: 50.9190, 14.0567