The remains of the Castle can be visited
Kropfenstein Castle (Ruin) (Waltensburg)

The Kropfenstein ruin in the municipality of Waltensburg in the Swiss canton of Graubünden is a historic castle, once one of Waltensburg's four significant fortifications. Its construction nestles against the rock like a natural growth.
History+
The origins of Kropfenstein Castle date back to the early 14th century, with dendrochronological studies suggesting 1312 as the construction year. There is no evidence of earlier structures at this site. The name "Kropfenstein" derives from the Old High German word "Kropf," meaning an excrescence or growth, describing the castle's position on the steeply sloping rock face. In the Middle Ages, the castle was inhabited by a family who served, among other things, as bailiffs and district judges. Documentary evidence for the builders is lacking, but the Kropfenstein family, possibly originating from Luven, is mentioned in various 14th and 15th-century documents. Among the representatives was Marquart von Kropfenstein, who served as a district judge for the Grey League in the 15th century. Towards the end of the 15th century, the Kropfenstein lineage died out, and the castle began to decay.
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: 46.7696, 9.1015