The fort at Halton Chesters was built across the line of the wall facing north, halfway between milecastles 21 and 22 about east of Dere Street. The original Hadrianic fort was rather squat in outline, almost square, measuring some 440 feet north-south by 400 feet east-west, with an area of just over 4 acres (c. 134 x 122 m; 1.6 ha).
