Milecastle 80

Each milecastle on Hadrian's Wall had two associated turret structures. These turrets were positioned approximately one-third and two-thirds of a Roman mile to the west of the Milecastle, and would probably have been manned by part of the milecastle's garrison. However, on the assumption that Hadrian's Wall terminated at Bowness, it is assumed that any structures to the west of Bowness would be part of the Cumbrian Coast defences beginning with Milefortlet 1. The possible turrets between Milecastle 80 and Milefortlet 1 are known as Tower 0A (grid reference NY217624) and Tower 0B (grid reference NY212622). There is currently no evidence for the existence of either tower.^[4][5]

• http://en.wikipedia.org/wiki/Milecastle 80