54. How many turrets were there on Hadrian’s Wall?

There were two turrets between each milecastle, so there was a notional total of 160 (assuming turrets existed between Milecastles 73 and 76). However, a number of additional turrets are known, where a pre-existing tower was incorporated into the Wall, as at Pike Hill (a short distance east of Turret 52A) and Turret 45A, or a new turret was added for tactical reasons, as happened with the Peel Gap tower between Turrets 39A and 39B. Thus it is possible that there were other, as yet undiscovered, additional turrets, so it seems 160 was a minimum.

Further reading: Breeze and Dobson 2000; Symonds and Mason 2009