These two circles ARE both plainly visible once you get your eye in but you do need a 1:25 000 map, and to enter the field marked as containing them. Although there is plenty of 'clitter' of unrelated stones the bigger circle in particular will suddenly appear - a few low uprights and some prostrate stones, and an appearance of embankment. Only one upright survives of the smaller circle, but it can still be distinguished. A good 'break' point on the walk up to Hengwn cairns from Tal-y-Bont.
Something is not right. This message is just to keep things from messing up down the road