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 to the east. After most of the forts had been added, the Vallum was built on the southern side. The wall was thus part of a defensive system which, from north to south, included: From Milecastle 49 to the western terminus of the wall at Bowness-on-Solway, the curtain wall was originally constructed from turf, possibly due to the absence of limestone for the manufacture of mortar. Subsequently, the Turf Wall was demolished and replaced with a stone wall. This took place in two phases; the first (from the River Irthing to a point west of Milecastle 54), during the reign