showing also the many intrusive objects that make photographing it difficult! There is a group of huts and ritual site on Dartmoor, probably of similar age, that gives me the impression that careful use of a flare and reflecting pool inside would have sacred the living daylights of anyone being forced to enter - and thus preserving the power of the ruling caste. Totally different from Belas Knap ( http://www.stone-circles.org.uk/stone/belasknap.htm )on the Cotswolds with a straight entry passage, yet scary enough. Both have an isolated stone believed to be a false entrance to put off grave robbers when the barrow was covered over.

http://www.english-heritage.org.uk/daysout/properties/arthurs-stone/history-and-research/