Hadrian's Wall

Begun in AD 122 during the reign of the emperor Hadrian, the wall was built as a stone rampart, turf-built along its western third, running some 80 Roman miles — about 73 modern miles, or 117 kilometres — from Wallsend on the River Tyne to Bowness-on-Solway on the Solway Firth. Three legions, the Second Augusta, Sixth Victrix and Twentieth Valeria Victrix, some 15,000 soldiers in total, raised most of it in around six years. Forts holding roughly 600 men each stood along its length, with smaller milecastles garrisoned by 12 to 20 men positioned about every Roman mile and watch-turrets between them roughly every third of a mile. A large ditch-and-mound earthwork known as the Vallum ran close to its southern side for almost the whole route.

The wall's purpose combined several functions: slowing raiders who crossed to take livestock or captives, channelling and taxing movement between the province and the unconquered north through its gates, and declaring Roman power at the empire's edge. Traces suggest it was originally plastered and whitewashed, which would have made its surface visible for miles.

Once fully manned, close to 10,000 auxiliary infantry and cavalry were stationed along the wall, separate from the legions who had built it. After Hadrian died in 138, his successor Antoninus Pius pushed the frontier some 100 miles north, building the turf-built Antonine Wall from 142 and leaving Hadrian's Wall garrisoned only in a support role. The Antonine Wall was abandoned within a generation, and Marcus Aurelius reoccupied Hadrian's Wall as the main frontier line in 164. Septimius Severus campaigned into Caledonia in 208–211 and briefly reoccupied the Antonine Wall again, but the campaign ended inconclusively and Roman forces withdrew back to Hadrian's Wall, which then stayed manned for roughly two more centuries.

Soldiers, their families and other immigrants who settled around the garrison may have made up 22 to 30 percent of the region's population. South of the wall, Roman-style settlements appeared within decades of its construction; north of it, native timber roundhouse settlements largely disappeared, and some scholars read this as evidence the Romans may have cleared the zone immediately beyond their frontier.

Roman administration and its legions had left Britain by about 410, and archaeology shows parts of the wall stayed occupied into the 5th century, possibly held by local Britons under a former Roman commander. The wall then fell into ruin and its stone was steadily quarried for other buildings; by the 7th century, worked stone from it had gone into St Paul's Church at Monkwearmouth-Jarrow, whose monk Bede lived his whole life close to the wall's eastern end and described it in his own writing — the church's dedication stone is dated 23 April 685. Much further stone-robbing followed in the 18th century, when General Wade used long stretches of the wall to build a military road for moving troops against the Jacobite rising of 1745.

The wall's survival owes much to the antiquarian John Clayton, town clerk of Newcastle, who inherited the Chesters estate and from 1834 began buying land along the wall specifically to stop farmers carrying off its stone, eventually controlling the stretch from Brunton to Cawfields that takes in the forts of Chesters, Carrawburgh, Housesteads and Vindolanda. He excavated at Cilurnum and Housesteads and used profits from his farms to fund restoration, generally rebuilding sections up to seven courses high; the best-preserved example of his work stands at Housesteads. After his death the estate passed to relatives and was lost to gambling, and the National Trust subsequently acquired much of the land on which the wall stands.

Hadrian's Wall was declared a UNESCO World Heritage Site in 1987, and in 2005 became part of the transnational "Frontiers of the Roman Empire" site alongside Roman frontier remains in Germany. It is now managed by English Heritage and remains unguarded, and the Hadrian's Wall Path National Trail, opened in 2003, follows its line from Wallsend to Bowness-on-Solway.