The remains of the Castle can be visited
Rohan Castle (Ruin) (Susch)

East of Susch in the canton of Graubünden, Switzerland, lies the Rohan Ruin, a former castle.
History+
Fortress Rohan was constructed in 1635 by Duke Henri II de Rohan. This occurred during the Thirty Years' War, during the Bündner Wirren, as battles raged for the reconquest of the Veltlin. Its strategic location provided rear cover against Spanish and Austrian troops. After the cessation of hostilities, the complex was abandoned. It remains unclear whether a defensive structure existed at this location earlier; any potential traces would have been removed by the 1635 construction. The star-shaped fortress still features wall heights ranging from 2.5 to 5 meters, with a wall thickness of 0.5 to 1.5 meters. A wooden battlement, whose supporting beams are preserved, ran below the top of the wall.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 46.7483, 10.0835