Stonea camp is an Iron Age hill fort located near March in the Cambridgeshire Fens. Situated on a gravel bank just 2 metres above sea-level, it is the lowest hill fort in Britain. Around 500 BC, when fortification is thought to have begun at this site, this 'hill' would have provided a significant area of habitable land amidst the flooded marshes of the fens. The site exhibits at least two phases of 

development over several hundred years of settlement, with a D-shaped set of earth banks surrounded by a larger, more formal set of banks and ditches.