Several comparable enclosed constructions have been found on the main land of western Europe, that are associated with Iron Age Celtic culture. These enclosures have square or rectangular plans of at least 15 x 15 meters, and are commonly known as viereckschanzen (which is German for four-corner-entrenchments). A viereckschanze is surrounded by a moat or an earthen barrier, and its corners generally point toward the four wind quarters. An entrance can be found on the southern or south-eastern side, but note that the constructions have no roof. Most of these buildings have been found in uninhabited areas.
In the case of the viereckschanzen, most scientists think they might have functioned as sanctuaries out in the open-air. This is based on finds of deep shafts and offering pits with remains of humans, animals and objects such as coins, small metal wheels. fibulae (decorative brooches), bracelets, weapens and parts of carriages. Some of thise objects have been broken on purpose, which points towards an offering – either to gods or ancestors. But note that not all viereckschanzen contains these finds, so their definite function is still debated.
Viereckschanzen may also have been used as courts and trading places – very much like large temples and churches in later ages.
Clerinx, Herman. Kelten en de Lage Landen. Leuven: Davidsfonds. 2005. (Second print.)