King Arthur's Hall is a megalithic enclosure on Bodmin Moor in Cornwall, England. It is thought to be a late Neolithic or early Bronze Age ceremonial site.
The monument consists of fifty-six stones arranged in a rectangle with a bank of earth around them and measures approximately 20m by 47m. The interior fills with water and a contemporary ground level has not been established. It has suffered damage by cattle in the past and is now protected by a gated fence. It can be reached by footpaths east of St Breward.
The surrounding area contains many stone circles, hut circles, cairns and cists.
In the absence of any archaeological finds, its origin and use is only speculative. A similar enclosure exists in Brittany which was a Bronze Age cremation site, but a similar rampart construction at Lough Gur in Ireland suggests an earlier Neolithic date. It has even been suggested that it was merely a medieval cattle pound, but the effort required to build the bank and to erect the slabs suggests that it had a more important function.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.