To the south of the market, the crest (495 m) of a wooded mountain forms a small rock plateau that supported the stronghold, the lower parts of the complex are on the side of the mountain facing away from the market. The castle path winds around the western slope of the castle hill and climbs from the southeast to a round, approximately 8 m high gate tower. This has a short wall approach to the outside. The tower did not initially function as a gate tower; the castle entrance was further north.
Remnants of the defensive wall pull up from the tower through the wooded slope to Berchfrit. From the "gate tower" the further access leads only slightly uphill northwards. The name Zwinger is not fully justified because the castle wall runs on the mountain side, but there is no boundary wall on the valley side. Further to the north, the missing wall is replaced by lining walls that lead to a square bastion in front of the castle entrance. The inner boundary wall of the "Zwinger" is partially upright, two shell towers are inserted into it, in the southeast with a horseshoe-shaped, in the northeast with a square plan.