The two small rooms had doors to the outside on the short end and could be accessed from the large middle room in the inside.
It would have enabled control of the traffic on the main land route between Aalborg and Aarhus.
Like the other ring castles (or forts) at Aggersborg or Trelleborg near Slagelse it is designed as exact circle with four gates opposite to each other and connected by two wooden roads that cross in a right angle in the exact middle of the fort. In each of the four quarters stood four Longhouses of the same design arranged in a square with a smaller house in the middle.
The middle row was as high as the earthwork and carried the inner side of the walkway.
The earth fill sloped to the inside so the ramparts could be easily accessed from every point of the circle road.
Along the outside ran a row of posts slanted to the wall either to support it at the top like buttresses or maybe even in some sort of cruck like construction being the rafters of the roof.
On how the roof was built exactly the opinions differ.
They were 28.5 meters long (96 Roman feet of 29.6 cm), 5 meters wide at the ends and 7.5 meters in the middle, the long walls slightly curved to the outside.
The walls consisted of double rows of posts with planks wedged horizontal between them to make a wall.
The inner diameter of the ramparts was 120 meters and the width at the base 12–13 meters.
They were constructed of three rows of vertical wooden poles. The innermost row was the lowest and the gaps filled horizontal with planks forming a wall to the inside of the fort.
The outer row of poles was strengthened on the inside and outside with slanted beams at the base.