All the walls and ramparts on the mountain are believed to belong to the ancient hillfort. There are also walls or remains of walls at clefts in the rock that could give access to the mountain. The walls have a combined length of 1525 metres and in places are difficult to identify or locate exactly. Halleberg is the largest hillfort in Scandinavia.
The Storegård cleft in the south-west, the only vehicle access route on to the mountain, is the entrance to the Draget valley. A system of dikes and fortifications were constructed here to prevent enemies from forcing their way up. Here, and in the Russ cleft, south-east of the valley, are the remains of masonry walls. Next to Bomstugan, the last building to the left of Storegårdsklev, can be seen the remains of the penetrated ramparts.