The milecastle measures 18.5m east to west by 21.3m north to south, substantially larger than many other milecastles. Two rows of buildings are visible within, probably barracks, one either side of the north-south road running through the gateways. Interior buildings are not normally so well-preserved or substantial in other milecastles and it is remarkable that local people, "mining" the milecastle for building stone in the past, may have recognised the layout as similar to stable-blocks. The walls are broad gauge, including stub 'wing walls' which connect with the Narrow Wall curtain of Hadrian's Wall on either side. It has Type III gateways and lies 1521m west of Milecastle 47 and 1458m east of Milecastle 49.