Thus, presumably the name was transferred from the hill, which is made of keratophyre (green volcanic rock), to the castle and adjacent settlement.

Other explanations relate the name to a hunting place, an idol or the Old High German word billi for "sword".

The northwestern wing of the main ward and the central block in the southwest are historical structures.

On the valley side of the central block is a portal terrace (Söller) on which a prominent lime tree is growing.

The outer bailey comprises three buildings, which are referred to as the gatehouse, timber-framed house and festival hall.