Roman Cumbria to Wallsend on the Tyne estuary, with additional military installations running down the Cumbrian coast from Bowness to Risehow, south of Maryport, in an integrated fashion (and with forts at Burrow Walls and Moresby that were perhaps not part of the system). Historians believe that the Turf Wall from the River Irthing to Bowness-on Solway was rebuilt in stone in two stages. The most easterly five miles were rebuilt at the time of Hadrian, with the remainder being rebuilt after 150 AD. However, this is open to dispute: it is uncertain whether the building works in the second half of
Hadrian's Wall of Hadrian, and the second following the reoccupation of Hadrian's Wall subsequent to the abandonment of the Antonine Wall (though it has also been suggested that this second phase took place during the reign of Septimius Severus). The line of the new stone wall follows the line of the turf wall, apart from the stretch between Milecastle 49 and Milecastle 51, where the line of the stone wall is slightly further to the north. In the stretch around Milecastle 50TW, it was built on a flat base with three to four courses of turf blocks. A basal layer of cobbles