Around 3200 B.C.E., farmers in Wales's Preseli Hills built a great monument: They carved columns of dolerite, or bluestone, from a nearby quarry, then thrust them upright in a circle aligned with the Sun. Exactly what the circle meant to them remains a mystery. But new research reveals that several centuries later, their descendants took down many of the giant stones and hauled them 200 kilometers to the Salisbury Plain. There, they created what is still the world's most iconic prehistoric stone monument: Stonehenge. The paper presents a "brilliant hypothesis" that Stonehenge is a dismantled stone circle from Wales.