Turret 45a (Walltown), Hadrian's Wall

Turret 45a is located high on Walltown Crags on Wall Mile 45 of Hadrian's Wall, about 1 mile north-west of the village of Greenhead in Northumberland, and just under ½ mile north-west of Walltown Visitor Centre. The turret is on the Pennine Way and Hadran's Wall Path. Turret 45a is unusual in that a) it is located further east, compared to the normal spacing between turrets and mile castles on Hadrian's Wall, and b) it was constructed without wing walls, with the curtain wall abutting the structure, rather than being integrated with it. These features are consistent with the suggestion that it might have been a signal tower which pre-dated the wall, built as part of a system of watchtowers associated with Stanegate (Roman road). The turret is included in a Grade I listed section of Hadrian's Wall, Milecastles and Turrets, and part of an ancient monument on the National Heritage List for England.

Turrets on Hadrian’s Wall were small watchtowers built into the wall, with two turrets per Roman mile, located between larger milecastles. They provided elevated viewpoints for small groups of 4 to 6 soldiers to spot threats and offer basic shelter for patrols. Turrets significantly enhanced continuous surveillance and control of the frontier by housing sentries between main garrisons. Their importance lay in forming an integrated part of the wall’s defensive system, enabling rapid communication and constant vigilance against incursions, turning the wall into a manned frontier rather than a simple barrier. Under a naming system introduced in 1930, turrets are numbered 1 to 80 from east (A) to west (B) and given numbers as pairs, taking the number of the nearest milecastle to their east.