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
Cromarty Firth it is about 5 miles (8 kilometres) wide, and Alness Bay where it is 2 miles (3.2 kilometres) wide, it has an average width of 1 mile (1.6 kilometre). The southern shore of the Firth is formed by a peninsula known as the Black Isle. Good views of the Cromarty Firth are to be had from the Sutors or Cnoc Fyrish. At its head the Firth receives its principal river, the River Conon, other rivers include the Allt Graad, Peffery, Sgitheach, Averon and Balnagown. The Dingwall Canal remains connected to the Firth, although it is now disused. The principal settlements