Cissbury ring is a National Trust site spanning multiple ages.

The univallate hillfort, which is the most obvious feature at Cissbury, was constructed c.400 BC and presents, at its largest, as a 5 metre wide and 2 metre deep ditch with 4 metre high banking enclosing an oval site of around 24 hectares (240,000 square metres). It is reasonable to assume that the ditch was deeper and the banking higher when the fort was constructed as 2,400 years of erosion would have lowered the banking and filled the ditch. There is evidence of field systems showing that most of the hillfort was being cultivated during the Iron Age.

The site has seen human activity for a far longer period of time, hosting at least 270 Neolithic (4300 bc to 2000 bc) Flint mines which present as circular depressions between 3m and 36m in diameter and up to 3 metres deep across the south western end of the fort. These are the backfilled remains of shafts dug into the chalk to reach the seams of flint and horizontal galleries radiate out from them. Piles of spoil are also evident.

Just outside of the fort are two Bronze Age bowl barrows and evidence of Romano British occupation in the form of at least 11 closely spaced rectangular depressions measuring 5m by 11m, as well as four much larger banked enclosures in the northern and eastern areas of the fort. There are traces of medieval era ridge and furrow field systems within the fort, as well as a Holloway leading into the fort from the south east.

More modern uses include a Napoleonic era beacon, close to the flint mines, and World War Two gun placements to the north of the fort.

I have also posted 118 handheld photos of the fort (and wider area) which can be viewed at http://www.iansapps.co.uk/outings/20230528.html