The remains of the Castle can be visited
Belmont Castle (Ruin) (Flims)

Northeast of Flims in the Swiss canton of Grisons are the ruins of Belmont Castle. Its position on a rock once offered far-reaching views.
History+
The earliest datable finds, including a spur, indicate that Belmont Castle was built around the turn of the 10th to the 11th century. It served as the ancestral seat of the Belmont family, who were among the noble free lords of the Vorderrhein valley and owned extensive properties in Flims, Vals, and Lugnez. A Lutefridus de Belmont is first mentioned in a document in 1139. The family was related to the Barons of Vaz and provided canons to the Diocese of Chur, and even a bishop, Konrad III of Belmont.
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: 46.8456, 9.3342