About 1570, when the Groengaard region was still thickly wooded, Duke Hans the Older built a hunting castle, probably designed by the architect Hercules von Oberberg. This three-storey building with its four corner towers and a projecting stair turret stood in a manmade lake. The south facade boasted a gallery borne by columns, one of which now stands near the bridge. This column was probably originally from an older building. After the death of Duke Hans in 1580, the castle was rarely used, and in the middle of the 17th century it was demolished. Examples of the elaborate sandstone ornamentation and other features of the castle may be seen at Tønder Museum.