One of the hills in the vicinity is fortified with a great ancient earthwork and ditch.
Its construction drew much attention to the subject of masonry dams in England - where the earthwork dam, with a wall of puddled clay, had hitherto been almost universal - and since its completion nine more masonry dams of smaller size have been completed.
At its head are the remains of a camp, connected with the Giant's Hedge, a raised earthwork which extends for 7 m.
At Bury Bank, on the hills to the north, an earthwork is traditionally considered to be the site of the capital of the Kingdom of Mercia; there are other works in the neighbourhood at Saxon Low.
Framlingham (Frendlingham, Framalingaham) in early Saxon times was probably the site of a fortified earthwork to which St Edmund the Martyr is said to have fled from the Danes in 870.
In the time of Edward the Confessor the town seems to have consisted of the mill and a fortification or earthwork which was probably thrown up by Alfred as a defence against the Danes; but it had increased in importance before the Conquest, and appears in Domesday as a thriving borough and port.
Hadrian Allcroft, Earthwork of England (1909).
The other, which begins where the earthwork stops, is a wall, though not a very formidable wall, of stone, the Teufelsmauer; it runs roughly east and west parallel to the Danube, which it finally joins at Heinheim near Regensburg.
An earthwork known as Castle Rough, in the marshes below Milton, was probably the work of Hasten the Dane in 892, and Bayford Castle, a mile distant, occupies the site of one said to have been built in opposition by King Alfred, Tong Castle is about 2 m.
On the seaward side of the Ness there is a large ancient earthwork which is attributed to the Norsemen through a reference in the Saxon Chronicle (894) under the name Sceobrig.