fogou

2009, Patricia Monaghan, fogou, entry in The Encyclopedia of Celtic Mythology and Folklore, page 198, Underground stone chambers found in Cornwall, believed to have been built between between 500 B.C.E. and 500 C.E., fogous appear to have been places of ritual. As there is evidence of occupation by Celts in the latter part of that period, it is possible that the fogous were built by or used by them, although evidence suggests a pre-Celtic spiritual vision.