Casterley Camp, Wiltshire
Casterley Camp, an entrenched area of 64 acres in Salisbury plain, Wilts, 8½ miles SE of Devizes. It is surrounded by a single vallum 28 feet high, and has a sacred circle in the centre. Sir R. C. Hoare pronounced it " one of the most original and unaltered works of the British era in the county."
Online maps of Casterley Camp are available from a number of sites: