Together with the Türmers Tower 180 meters away, the Fehn Tower marks the boundary of the medieval inner town. The tower, measuring in at 28 meters, was built in the 13th century and flanked the lower gate to the inner town fortification. It is named after the Fehn family. The tower has also been used as a prison as well as a town museum since 1908. You can visit the tower today as part of guided town tours.