The Tertiary volcanic dome of the Barsberg was the highest elevation (600 m) in the vicinity and particularly suitable for the construction of a ring wall. Their builders deliberately chose the location and were guided by the natural conditions. They strengthened the basalt wall at weak points and regulated access via a narrow ascent from the west. At the southern tip there was probably a watchtower, because the volcanic stones are still about 4 m high. In principle, the layout of the access gate has been preserved until the Middle Ages. Behind the ring wall, which, with the exception of part of it on the north side of the complex, has been preserved, there was a ditch about 2 m deep, which can still be clearly seen on the northeast side. The masonry was built without mortar. Since only around 300 BC Chr Mortar was used, this meant that the ring wall system is at least 2,200 years old.