Black Ditches is an earthwork close to the village of Cavenham of Suffolk, and part of it is a biological Site of Special Scientific Interest. The earthwork is 4.5 miles long between the River Lark at

Fleam Dyke is a linear earthwork between Fulbourn and Balsham in Cambridgeshire, initiated some time between AD 330 and AD 510. It is three miles long and seven metres high from ditch to bank, and its