In Odenthal, behind the town hall and the parish church of St. Pankratius, there is a well and a memorial plaque commemorating the witch trials. The Witches Fountain was created in 1988 by the sculptor Walter Jansen. Wikipedia
The Witches Route is a theme trail that started and ends in Odenthal. You pass some places where witches used to mischief. A nice, not too long hike. The Witch Fountain in Odenthal can serve as the start and end point of the route.