Cissbury Ring is a hillfort on a chalk spur about 3km north of the Channel at Worthing. Roughly oval, about 24 hectares, built in the Middle Iron Age around 400 BC. Bank 1.3m to 3.9m high, ditch about 5m wide and 2m deep.
The part that stayed with me: the bank is biggest on the south-east, where the ground slopes away gradually and someone could actually walk up. Where the hill defends itself, the wall gets lazy. Where it doesn’t, the wall works.
The hill was busy long before the fort. Under the south-west lies a Neolithic flint mine: at least 270 hollows, 3m to 36m across, shafts dug to the flint seams. One of only about 20 recorded nationally. Then a Roman settlement inside the fort, medieval ploughing, a beacon John Aubrey mentions, a Napoleonic infantry post, and a WWII anti-aircraft position whose three rings still sit there.
A stack, each layer using the last.
Sources: Historic England NHLE 1015817; Donachie & Field, A Survey of Cissbury Ring (1993).
I do like your notes - I recall being somewhat overwhelmed by the sheer scale of Cissbury, but you give punters a place to start. More, please.