Many people are interested in the matter of the "lost well" of St Brynach, not far from the tors of Carnedd Meibion Owen. Having been up there to check it out, and to look at the circle (which is probably of not much significance), I think that the marked position of Buarth Brynach is not very convincing. Yes, there is a small ditch or drainage route running downslope, but where the well is supposed to have been it is quite dry, with a gap in the hedge and a big patch of nettles. But about 60m away, to the NE, there is a distinct mound in the field, with very prolific grass growth around it and a cluster of rushes as well. The surface is quite irregular. I wonder if this is a pile of rubble that might mark the position of an old well or enclosed spring? Grid ref: SN 09198 35746.
"Buarth" means an enclosure or fold, so this might be further confirmation. The mound needs to be explored!