About A.D. 81, Julius Agricola, in order to protect the northern limits of the Roman territories in Britain, against the incursions of the northern barbarians, extended an artificial rampart or vallum, consisting of a chain of forts, across the island, from Tynemouth to Bowness, a distance of about seventy-four miles, in a parallel line with the northern shores of the Tyne and Irthing; and in the yeare 121, Adrian commanded a more formidable rampart or military fence to be raised, which was carried on from Solway Frith to Wallsend, on the Tyne, nearly four miles below Newcastle. Near the hamlet of Portgate it consists of a mound of earth, nineteen feet broad at the base, and almost ten feet high; and there is, about sixteen feet north of this, a second mound, ten feet broad at the base, with a ditch on its north hide, twelve feet deep and twenty-eight feet wide; and twenty-eight feet north of the ditch there is a third mound of earth, thirty-three feet broad at its base.

These four works keep all the way a regular parallelism one with the other. The most northern is supposed to have been the military way to the ancient line of forts, erected by Agricola, as it undoubtedly was to this four-fold barrier; and the southern mound was thrown up for an inner defence, in case of a sudden attack from the provincial Britons. Some authors affirm that Severus built a wall of stone, others a vallum of earth, and others, amongst whom is Richard Cirencester, avow that he only repaired the wall of Adrian, about the yeare 208, and that the solid stone wall which stretched from sea to sea, was erected after the yeare 416, by the Britons and the last legion of Roman soldiers sent to this country. The height of the wall was twelve feet, exclusive of the battlements, which were four feet; and its thickness, eight feet. A paved military way attended it every where, from one extremity to the other; and upon it were seventeen or eighteenestations, and eighty-one castles, besides about 324 watch towers or turrets. The stations were occupied by the Roman cohorts, and were large and strong fortresses, strengthened by deep ditches and thick walls, having the great wall itself for their northern boundary. These stations were not placed at regular distances from each other, but stood generally thickest neat both ends and the middle of the walls, probably on account of those places being considered more exposed to danger. Without the walls of each station was a town, inhabited both by Romans and Britons who chose to dwell wider the protection of the garrison.