Chanctonbury Ring

Chanctonbury Ring is a prehistoric hill fort atop Chanctonbury Hill on the South Downs, on the border of the civil parishes of Washington and Wiston in the English county of West Sussex. A ridgeway, now part of the South Downs Way, runs along the hill. It forms part of an ensemble of associated historical features created over a span of more than 2,000 years, including round barrows dating from the Bronze Age to the Saxon periods and dykes dating from the Iron Age and Roman periods.

Consisting of a roughly circular low earthen rampart surrounded by a ditch, Chanctonbury Ring is thought to date to the late Bronze Age or early Iron Age. The purpose of the structure is unknown but it could have filled a variety of roles, including a defensive position, a cattle enclosure or even a religious shrine.

Source: Wikipedia