Wall Mile 74 [HB 358]
As with Wall Mile 75, nothing is known about Wall Mile 74. This might therefore be a good time to consider the Turf Wall.
Initially, Hadrian’s Wall consisted of a stone curtain wall between Newcastle and the River Irthing (Wall Miles 4 to 48) and then a turf rampart from the Irthing to Bowness (49 to 79). The rampart, nowadays called the Turf Wall, was built on a base about 6m (20 Roman feet) wide with no foundation trench; in some places just laid turves, in others cobbles, were used as a base, but it seems to have depended what materials were available. The rear face sloped at an angle of about 67° and the front was vertical near the base and then probably sloped above.
The Turf Wall was equipped with turf and timber milecastles but stone turrets. These turrets, built free-standing and with the turf rampart then butted against them, were retained when the stone curtain wall was built. The ditch that was dug for the Turf Wall was retained for the Stone Wall, although the berm increased in width from around 1.9–2.4m (6–8 Roman feet) to 6m (20 Roman feet).
It is assumed there was some sort of wooden superstructure, such as a walkway and parapet, but almost no evidence has survived to support this. The one clue that there might have been a walkway comes from the fact that when the Turf Wall was replaced by a stone curtain, that stone wall was set back slightly from the front of the turrets. Some scholars have suggested this shows it was lined up with existing doorways on the turrets giving access to a walkway.
When forts were added, those in Wall Miles 49 to 79 started as turf-and-timber constructions (this has been shown by excavation at Bowness, Drumburgh, and Castlesteads, and presumed for Burgh, Stanwix, and Birdoswald).
Milecastle 74 (Burgh Marsh) [HB 358; haiku]
Naturally, Milecastle 74 (Burgh Marsh) has not been found.