We do have a number of stone circles in Cornwall (the Merry Maidens, the Nine Maidens and the Hurlers spring to mind) and we have lots of Bronze Age settlement remains on Bodmin Moor. Close to us we have the impressive hill fort at Warbstow Bury. Quite a few dolmens too, and there's Men an Tol ,a doughnut-shaped stone ring on its edge accompanied by a somewhat phallic standing stone pointing at it. What COULD it mean.. ;-) I think that most people who go to it crawl through the hole!