The Castle can't be visited
Königsegg Castle

Königsegg Castle stands on Reichenau Island in the district of Konstanz. Originally built as a ministerial seat of Reichenau Abbey, it has been altered multiple times and now serves a modern educational purpose.
History+
In the late Middle Ages, the site of the present castle was home to a ministerialis of Reichenau Abbey. In the 16th century, the Imperial Counts of Königsegg constructed a new building. In the 17th century, the property passed into the possession of the Augustinian Canons Regular of Beuron Monastery, who undertook renovations. Until the secularization at the beginning of the 19th century, the castle remained in ecclesiastical ownership.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://schloesserrundschau.de/bawue/schloesser/konstanz16.html
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: 47.6921, 9.0599