The remains of the Castle can be visited
Restiturm Castle (Ruin) (Meiringen)

The Restiturm ruin in Meiringen is a former noble residence that played a role in monitoring the Haslital valley and the Alpine passes.
History+
Restiturm Castle dates back to the mid-13th century, when it was built on a rockfall boulder. The complex underwent expansions, including an increase in the tower's height around 1300. It served as the ancestral seat of the Knights of Resti, who acted as feudal lords for the Habsburgs. Its location above the Haslital allowed for control of the valley and the trade routes over the Grimsel Pass, Joch Pass, Susten Pass, Grosse Scheidegg, and Brünig Pass. In the 16th century, the castle was abandoned and 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: 46.7268, 8.1962