Visited 24th May 2003: We made our way up to this site from the Waun Mawn Stone, but over-shot, and ended up approaching from the north west. The views from up there were incredible, even though the weather was changing from erratic to rainy.
Of the three stones that we could identify, only one remains standing in a circular puddle (yes, another deep muddy puddle for William to play near). Both the recumbent stones were clearly standing at some time, with identifiable holes where they once stood. Two of the stones (the ones to the east) are close together and the third stands a way off to the west. There was quite a good feeling to the place, and I reckon it would be extremely pleasant to sit up here on a nice day and enjoy some solitude.
This site is one of those ones that nobody can agree upon. The most interesting explanation is that it's the remains of a stone circle, but it's also been interpreted as a stone row, or just some sort of ruined megalithic structure. Here's what N.P. Figgis says about it in Prehistoric Preseli:
A group of stones, variously considered as a pair with one stone fallen and - least likely - remnants of a circle of which most are fallen. No early reference or place names suggest the presence of a circle; the three stones involved would indicate an enormous diameter. Interpretation open to suggestions!
I agree with Figgis that the circle would be whopping if that's what it was. Based on what I've seen I reckon it's a stone row.
The discovery of a dismantled stone circle—close to Stonehenge's bluestone quarries in west Wales—raises the possibility that a 900-year-old legend about Stonehenge being built from an earlier stone circle contains a grain of truth. Radiocarbon and OSL dating of Waun Mawn indicate construction c. 3000 BC, shortly before the initial construction of Stonehenge. The identical diameters of Waun Mawn and the enclosing ditch of Stonehenge, and their orientations on the midsummer solstice sunrise, suggest that at least part of the Waun Mawn circle was brought from west Wales to Salisbury Plain. This interpretation complements recent isotope work that supports a hypothesis of migration of both people and animals from Wales to Stonehenge.
Waun Mawn: a former stone circle near the bluestone quarries for Stonehenge by Prof. Mike Parker Pearson (in English).
In 2017 and 2018 the Stones of Stonehenge Project, led by researchers from University College London and the universities of Southampton, Bournemouth and the Highlands & Islands, carried out excavations at Waun Mawn in North Pembrokeshire to discover if the four monoliths there are all that is left of a prehistoric stone circle. These four monoliths – three of them recumbent and one still standing – form an arc which previous archaeologists have suspected may be remains of a circle. Our excavations discovered a further six empty sockets around the perimeter, revealing that this stone circle was originally 110m in diameter. This makes it one of the largest stone circles in Britain and the same diameter as the ditch around Stonehenge. The team have also been able to establish its age by radiocarbon dating and optically stimulated luminescence (OSL) profiling and dating.