The remains of the Castle can be visited
Hauenstein Castle (Ruin)

The Hauenstein Ruin, a former hilltop castle, is in Laufenburg-Hauenstein on a rocky ridge above the High Rhine. Its location once allowed control over important trade routes by land and water.
History+
The origins of the complex likely date back to the Early Middle Ages, possibly even to late antiquity, serving to secure the Säckingen Monastery and a border point. Until around 1500, Hauenstein Castle, an imperial fief, was the seat of the forest bailiwick of the County of Hauenstein and functioned as a customs post and a center for regional administration. The castle complex was rebuilt and expanded multiple times, with the oldest part probably located in the southwest and dating back to the 10th or 11th century.
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: 47.5820, 8.1065