The remains of the Castle can be visited
Castelberg Castle (Ruin) (Luven)

The Castelberg ruin is located below Luven in the canton of Graubünden, Switzerland. It marks the entrance to the Val Lumnezia.
History+
Its construction is dated to the first half of the 13th century. Archaeological finds from 1968/69, such as a knife blade from around 1300, animal bones, and a pottery fragment, suggest a short period of occupation. Castelberg presumably served as the residence for the episcopal vassal family of Castelberg, first mentioned in 1289 with Wilhelm. A document from 1391 mentions a 'colonia sur castiels' near Luven, which refers to the castle.
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: 46.7566, 9.2098