The greatest surviving monument of the Roman period in the north-east are the walls and forts of the fortified frontier known as Hadrian's Wall, which runs from the mouth of the River Tyne to the west coast of Cumbria. It cut across much of the lands of the Brigantes, which reached into North Northumberland. The first group of defences were associated with the Stanegate, built at the end of the first century AD by Agricola and Trajan. It had forts at Corbridge, Chesterholm (Vindolanda), Nether Denton and Carlisle; Carvoran and Old Church Brampton may also have been built at this time.
When Hadrian became emperor in AD 117 he found that 'the Britons could not be kept under Roman control'. He visited the province in AD 122 and decided not to attempt another invasion of Scotland but to defend Trajan's frontier. However, it was clear that a frontier which was defended by forts and watch-towers but no permanent barrier was not sufficient, so he decided 'to build a wall, eighty miles long, to separate the Romans from the barbarians'.
Initially the frontier was to consist of a curtain wall, 10 Roman feet wide, with a fortified gateway (known today as a milecastle) every Roman mile with two turrets between each pair of milecastles. No forts were planned to be built on the Wall as there were already forts on the Stanegate but before the frontier was complete a decision was taken to build forts on the line of the Wall. The forts built in Northumberland were Rudchester, Halton Chesters, Chesters, Carrawburgh, Housesteads, Great Chesters and Carvoran. The frontier was built by the Second, Sixth and Twentieth Legions.
In the central sector the Wall followed line of the craggy outcrop known as the Whin Sill but in the lowland sections a ditch was dug to the north of the Wall. The Wall itself is thought to have stood up to 5 metres in height and was made from stone cut locally. At Haltwhistle Burn the soldiers left graffiti carved onto a quarry face. Behind the Wall a further defence consisting of a broad ditch flanked by two earth banks, known as the Vallum, may have protected the rear of the frontier and marked the military zone.
The Wall may not have been built merely to prevent raids from the North. It may also have acted as a customs post and travellers may have had to pay a toll to cross the frontier by one of its many gates. One gate which was not attached to a fort or a milecastle stood north of Corbridge where Dere Street crossed the line of the Wall. Although the gate itself can no longer be seen its name survives as Portgate.
To the north of the Wall outpost forts were built at High Rochester and Risingham and a fortlet built on the site of the earlier marching camps at Chew Green. To the south of the Wall the hinterland forts at Binchester, {Lanchester D1850}and {Ebchester D1911} were retained to provide protection in depth. There may also have been look-out-posts along the coast.
In the AD140s the Romans decided to move their border north, and built a new frontier, known as the Antonine Wall between the rivers Clyde and Forth in central Scotland. Many of the soldiers stationed on Hadrian's Wall were moved north to defend this new boundary.
Hadrian's Wall was broken through in places, although it was not completely abandoned. This meant it was easy to repair when the Romans withdrew from the Antonine Wall in the 160s and returned to the Tyne-Solway line. Despite further campaigns into Scotland over the next two centuries Hadrian's Wall remained the northern frontier of the Empire until the end of the Roman period.
Today Hadrian's Wall survives as a mixture or upstanding consolidated walls, earthwork ditches and banks and buried remains. The whole route of the Wall is designated as a World Heritage Site.