Our verdict
An easy, atmospheric wander through a genuinely odd landscape feature — no big climbs, just a valley full of huge weathered boulders. Good for a short stop combined with Fyfield Down or West Woods nearby.
Two sheltered valleys either side of the A4 near Lockeridge, each strewn with 'boulder streams' of sarsen stones — the same silicified sandstone used to build Avebury and Stonehenge, broken up and shifted here in the last Ice Age. Lockeridge Dene lies south of the A4, Piggledene to the north, and both have been National Trust land since 1908; the stones' lichen makes them a haven for insects and birds.
National Trust land — usually free to walk; some sites charge for parking.