Our verdict
One of the more geologically distinctive spots in this guide — genuinely odd and worth seeing — but there's no café or facilities, so it's a there-and-back from Littlebredy rather than a full day out.
A dry chalk valley scattered with sarsen stones — a boulder train exposed by the last Ice Age and, by tradition, a likely source of some of the standing stones on the Ridgeway. Calcareous grassland here supports a rich mix of butterflies and wildflowers, managed as a National Nature Reserve.
National Nature Reserve — one of the country's finest wildlife sites. Open, but stick to marked trails.