Coombe Bottom, Kelshall
Aerial photographs taken by the University of Cambridge in the 1960s had revealed a square ditched enclosure and a curious arrangement of five large pits, like the 5 dots on a dice cube, in a field on the route of the widening and dualling of the A505 between Baldock and Royston. Archaeological excavation during the roadworks uncovered the full extent of both features and both were totally excavated to the chalk bedrock. Such little dating evidence as there was showed both features to be Iron Age in date. They were possibly used for some short-lived ritual or ceremonial event. The ditches of the square enclosure had been rapidly in-filled with the chalk nodules that had been excavated out of them, very soon after their original excavation. There was only a small deposit of silt at the bottom of the ditches; enough to have been washed down during one heavy rainstorm. The five large pits proved to be post-holes which had contained massive, one metre diameter timbers, probably whole tree trunks. Possibly these posts supported a large platform, about 3.5m square, designed to take a considerable weight, maybe people viewing whatever activity took place within the square enclosure.
To one side of these prehistoric features, the ditches and wheel-ruts of a post-medieval road (17/18th century) were revealed, coming down the hill from Sandon to join the Icknield Way (A505), heading towards Royston.