Prof. Mike Parker Pearson @ Waun Mawn
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.
The site is indeed an exciting and atmospheric one, but it's worth noting that Darvill didn't feel that the evidence was good enough for the stone circle conclusion:
cambridge.org/core/journals/antiquity/article/mythical-rings-waun-mawn-and-stonehenge-stage-1/2F089B76AA2411BB09DBAFE79060101F