His story
Hadrian was unusual among emperors: he spent years touring the provinces.4 In AD 122 he came to Britain, and visited London with his wife, the empress Sabina.4 A biography written about two hundred years later says that he “put many things to right and was the first to build a wall 80 miles long from sea to sea to separate the barbarians from the Romans”.1
The first plan
By about AD 100 the most northern Roman forts already lay along a road, now called the Stanegate, between Corbridge and Carlisle. The Wall was put slightly north of them. As first planned it was a wall of stone in the east and turf in the west, with a guarded gate every Roman mile, two watchtowers between each pair of gates, and a wide, deep ditch in front. The soldiers would stay in the forts behind.1
It was built mostly by the three legions of Britain, each about 5,000 trained heavy infantry, helped by auxiliary units and even the British fleet. It was surveyed from each end towards the crags in the middle, in sections.1
The change of plan
Before the first plan was finished, it changed. Forts were moved onto the Wall itself, about seven and a third miles apart, built across it where they could be so that soldiers could get out to the north quickly. Chesters and Housesteads are two of them.13 Then a huge earthwork, the Vallum, was dug behind the Wall: a ditch between two mounds, about 35 metres across. To finish faster, the Wall was narrowed from 10 Roman feet to 8 or less, and built less carefully.1
The Wall may even have been begun before Hadrian arrived, and his visit may be what changed the plan. No one knows for sure.1
After Hadrian
Hadrian died in AD 138. His successor, Antoninus Pius, abandoned the Wall and built a new one, of turf, between the Forth and the Clyde. It lasted about twenty years before the army came back to Hadrian’s Wall, which then stayed the frontier until the end of Roman Britain. The latest coins found on it were minted in AD 403 to 406.1