From quarries at Carn Goedog and Craig Rhos-y-felin in the Preseli Hills, where Neolithic workers split the rock more than 5,000 years ago.
Excavators found abandoned tools, stone wedges, and partly worked pillars still lying at the quarry faces. The rock there naturally splits into tall pillars, so builders could lever out ready-made standing stones rather than carving them from scratch.
