'The graves of the women': three cairns high up on the hills near the boundary of the parish of Llanymawddwy, not marked on the Ordnance sheet.
"When Garthbeibio was a chapel of ease to Llanymawddwy, three women started to walk to the mother church one Sunday morning in winter to be churched. But when they reached the height of the mountain a snow storm came on and enveloped them in darkness; and when a search was made for them, the three were found dead on the spot where these barrows were raised to commemorate the melancholy event, and to denote the spot where their mortal remains found a last resting place" (Mont. Coll., 1873, vi, 12).
Tradition adds that the barrows were raised by the women of this and the adjoining parishes, who collected the stones in their aprons, and carried them to the spot.
This grid reference is given on the Coflein map. I doubt it's the easiest spot to get to to check if there are three cairns. It also strikes me that if crossing boundaries is dangerous in a Welsh folklorish sense, then that must be particularly unwise on a windswept mountainside in the snow.