Rybury began as Neolithic causewayed camp, like nearby Knap Hill, and is thought to date from about 2500BC. The hilltop is encircled by ditches crossed by causeways. It seems an excellent site to choose: a naturally isolated flattish spot, surrounded by steep slopes on a spur of the downs, with wide views of the vale below.
Later an Iron Age enclosure was built here – this is the period the bank comes from. Dyer (in ‘Southern England, an Archaeological Guide’) suggests that the site’s eastern side shows the Neolithic ditches the best (the outer ditch being Neolithic, the inner being Iron Age?).