The archaeological mystery of Stonehenge's long-lost megaliths

Around 4,500 years ago, the famous silhouette of Stonehenge would have looked very different. Writer and archaeologist Mike Pitts digs up clues to the mystery of the circle's long-lost stones.

If you are fortunate enough to be at Stonehenge on midwinter day, 21 December, and also for the sky to be clear near the horizon as the Sun sets you can experience a striking event. Position yourself between the tall, outlying Heel Stone and the stone circle, and look south-west through the megaliths. In the closing darkness they appear like a huge crumbling wall, orange light slanting through vertical fissures. In the last quick moments, the Sun disappears from a window formed by two great vertical stones and the horizontal lintel they support. It's dark and cold. Stonehenge, it feels, has swallowed the Sun.

And many more upright stones have gone. What happened to these missing stones? Who took them down and where did they go? How do we know they were once there? Can we picture what the completed Stonehenge looked like? Indeed, was it ever finished at all?

These are questions that archaeologists like myself have asked for centuries. We can't answer any of them with certainty. But a long, active search has brought my colleagues and I closer. Through survey, excavation and geological studies have helped to clarify – sometimes in the most surprising ways – one of the big puzzles of Stonehenge: is that all there was?

Restoration and excavation resumed in the 1950s and 60s, when more buried holes were found, this time in amongst the present standing stones. Pits in two closely nested half-circles very likely held small megaliths, and other pits indicate that these stones were taken down and rearranged – with the addition of more stones – in a concentric oval and circle. These two were later adjusted to form the present arrangement of a circle and open-ended horseshoe, of which many stones have gone.

In one case, however, we know exactly who took some chips, when and why. They unlocked one of the most remarkable discoveries ever made about Stonehenge.