Situated high above the River Alme lies the village of Harth with its ruined Castle 'Ringelstein'. The time of the castle's construction is uncertain. It was first mentioned in a document dating back to 1409. In ancient literature, the castle is mentioned as a hunting lodge belonging to 'the Noblemen of Büren' and therefore must have been built around the year 1200. An inventory of the castle from the year 1574 states that at the time, it comprised of 12 chambers, one egg cellar, one wine cellar and one meat cellar, one kitchen, one brewery and one bakery, one cavalry stable and one corn loft.
In the 30 Year War, this castle was the stage for numerous witch trials. Evidence of these trials is found in the castle's witch cellar. In 1631, during a 4-week period, 50 people were found guilty and burnt as witches. Guided tours on request.