The remains of the Castle can be visited
Schleifenrain Castle (Ruin) (Kemmental)

In the municipality of Kemmental in the canton of Thurgau, the Schleifenrain ruin, a historic castle, stands on an elevation. Its location, surrounded by the ravines of the Kemmenbach and another stream, makes it a testament to medieval architecture in Switzerland.
History+
The origins of Schleifenrain Castle are presumed to date back to the 12th century. Archaeological excavations in the 1960s uncovered the foundations of a tower and an annex, but the exact ownership remains unknown to this day. It is believed that the castle once belonged to the Lords of Hugelshofen, who served as vassals of the Bishop of Constance.
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: 47.6039, 9.1019