The Original Stonehenge Was In Pembrokeshire
That's what Stonehenge's leading archaeologists have discovered - and it's been on BBC2 with a dedicated programme with Professor Alice Roberts, so it must be true.
We all know the story of some of Stonehenge's pillars (not the huge ones we recognise as Stonehenge) being dragged over 150 miles from Pembrokeshire's Preseli hills - the so-called bluestones.
What we've not understood is why. Professor Mike Parker Pearson and colleagues have now established the specific quarry the pillars came from - Carn Goedog - and that they were then taken just a couple of miles to Waun Mawn where they were erected as a large stone circle - probably the largest stone circle in Britain at that time.
What's perhaps even more surprising is that it was constructed upto 500 years before the same stones were transported to Stonehenge to become Stonehenge's own original Stonehenge before the monster one we now regard as Stonehenge was built.
The evidence, in addition to them being Carn Goedog stones, is that the stone circles at Waun Mawn and Stonehenge have almost exactly the same diameter, and one of the foundation pits at Waun Mawn exactly matches one at Stonehenge.
So, the reason for the huge effort required to take them to Stonehenge now becomes clear: they were ancient, powerful religious 'icons' belonging to one of Britain's most holy and most visited sites - and the priests of Stonehenge were determined to create the most impressive religious site in Britain.
The medieval church went to similar extraordinary lengths to build massive cathedrals, but what really attracted pilgrims from far and wide were the relics - the bones of saints, pieces of Jesus' cross, the Ark of the Covenant etc. Religions change, human beings change - but not much.
For Garn Goch, this was also significant for three reasons, and a theory: the Carn Goedog and Garn Goch stones look similar (see the middle pictures above); Garn Goch was not an outlier, but lay on the ridgeway 'camino' to Pembrokeshire's major pilgrim centre; it only became an outlier when Stonehenge became Britain's premier pilgrim centre.
Here's the theory: at the centre of Stonehenge is a massive stone called the Red Altar used almost certainly for - let's be blunt - human sacrifices, but that's not the only reason it's called red. Geological analysis in 2020  has confirmed it is a particular red sandstone that only comes from an area centred on the Senni Formation (as in Sennybridge), and found in the Sawdde Gorge below Garn Goch.
It's highly likely that Garn Goch would have had a similar Red Altar, given its proximity, and it's not impossible, given that Stonehenge's priests took Pembrokeshire's already ancient and holy stone circle, that they also took Garn Goch's already ancient and holy altar too.
The switch of pilgrims to Stonehenge, and the loss of its famous altar (if it was taken), would certainly have caused the decline of a once powerful and popular religious site. Garn Goch was left to sheep and cattle.
Left: Professors Roberts & Parker Pearson at Waun Mawn. Middle left: Professor Mike Parker Pearson at Carn Goedog. Middle right: Garn Goch pillars. Right: Red Altar at Stonehenge. See copyrights.