A university professor believes he has solved one of the oldest Stonehenge mysteries - the exact location in Wales where the bluestones were quarried.
Tim Darvill has found what he thinks is an ancient quarry at Carn Menyn high in the Preseli Hills of Pembrokeshire.
The bluestones - which form the inner circle of Stonehenge - were transported over 240 miles to Salisbury Plain.
Local archaeologists say Professor Darvill had made a "convincing and compelling" argument.
Writing in the July/August issue of British Archaeology, he describes the very spot from which be says the stones were quarried centuries ago.
He believes there is evidence at the site that it was used as a prehistoric quarry. Added to that the rock formations there are identical to those of the bluestones and the location of the quarry meant it would have been prized source of stone.
Earlier this year he and his colleague Geoff Wainwright led a field expedition to the site, which he describes as "a veritable Aladdin's Cave of made-to-measure pillars for aspiring circle builders".
He describes a "small crag-edged promontory with a stone bank across its neck" and measuring less than half a hectare as the exact location.
"Three things are clear from just looking around the site," he said.
"First, those outcrops have been exploited as a source of stone for a long time and much has been taken away.
"Second, our understanding of what a 'quarry' is perhaps needs to be modified because here the extraction of pillars simply involves leavening suitably shaped but naturally detached blocks from the ground or a fractured outcrop.
Professor Darvill led fieldwork at the site in April
"And third, the remoteness of the place and its mountain top situation invite comparison with other known sources of prized stone, exploited for axe heads during the fourth and third millennia BC."
Gwilym Hughes, Director of Cambria Archaeology, the south west Wales archaeological trust, said Mr Darvill still had some work to do to prove his theory beyond doubt.
But he said: "They have put forward a very reasoned argument which I found very convincing and very compelling.
"When you stand up on the site you can see what kind of hold and significance it would have had for prehistoric man, it's got a kind of aura about it.
"There are alternative theories put forward for the arrival of the Bluestones at Salisbury Hill including the possibility they have been taken there by natural forces such as glaciers.
"Personally I would like to think they have been taken there by human action."