The remains of the Castle can be visited
Fürstenstein Caslte (Ruin)

At the entrance to the Wallental valley, on a rugged rock ridge, lies the Fürstenstein ruin, a former castle in the Basel-Landschaft region, Switzerland. It is located on a very narrow, almost vertically rising limestone ridge, formed during the Jura folding.
History+
The exact beginnings of Fürstenstein Castle are unknown. It is presumed that the Lords of Rotberg were the builders, as they dominated the surrounding region. Fürstenstein was first documented in 1302 as an episcopal fief granted to the Rotberg family. During the conflict between King Albrecht and the Bishop of Basel, the fortress was besieged by the Habsburgs, but the siege ended abruptly with King Albrecht's assassination in 1308. An earthquake in Basel damaged the castle, but it was quickly repaired. In 1410, the former Basel mayor Hans Ludmann von Rotberg sought refuge here.
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: 47.4677, 7.5307