Pilsdon Pen Hillfort, Dorset.
Pilsden Penn hillfort is a multivallate Iron Age enclosure of approx. 7.75 acres (3.1 hectares), shaped a little like a Paramecium. Contains two Neolithic/Bronze Age mounds, and post-Medieval pillow mounds (rabbit warrens).
Gary Mortimer kindly pointed me in the direction of a point cloud model generated from a series photographs he took from a model aeroplane – the photosynth page can be found here.
OS map reference: ST 41252 01290. Nearest town/village: Broadwindsor.