The Castle can be visited
Museum
Pillnitz Castle

In Dresden-Pillnitz, a district of Dresden in Saxony, Germany, Pillnitz Palace is an example of 18th-century Chinoiserie. The complex consists of the Water Palace by the river, the Hill Palace on the slope, and the connecting New Palace, surrounded by a Baroque pleasure garden and a palace park.
History+
The origins of Pillnitz date back to the 14th century, when a manor house existed here, later expanded into a residential castle. In 1569, Christoph von Loß d. Ä. acquired the fief and laid the foundation stone for the palace church in 1594. After several changes of ownership, the palace came into the possession of Elector Johann Georg IV in 1694, who gifted it to his mistress.
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: 51.0089, 13.8702