Turret 41B, known as Thorny Doors, is a Hadrianic watch tower on the central crags sector of Hadrian's Wall, between Cawfields and Caw Gap in Northumberland. Built in the 120s AD as part of the original Wall scheme, it occupied one of the most dramatic positions on the entire frontier, where the Wall climbs and descends the steep Whin Sill escarpment. Like other turrets, it would have been a small stone tower (roughly 4–5 m square internally) housing a handful of soldiers from the garrison of nearby Milecastle 41 or 42, active through much of the 2nd century before likely abandonment as turrets were progressively decommissioned.
Source: Pleiades — A Community-Built Gazetteer and Graph of Ancient Places. View the Pleiades record →
Its primary role was observation and signalling along this rugged stretch of frontier, where the natural cliff-line itself provided much of the defensive strength. The site is particularly notable for preserving one of the tallest surviving stretches of Hadrian's Wall curtain immediately adjacent to it — up to 14 courses (around 3 m) high — giving an exceptional impression of the Wall's original scale.
The turret itself has not been extensively excavated and its structural remains are modest, but consolidation work and survey have confirmed the standard recessed-turret plan bonded into the broad-gauge Wall. The adjacent Wall section is among the best-preserved on the frontier and has been the subject of conservation recording, though detailed finds assem
Turret 41B, known as Thorny Doors, is a Hadrianic watch tower on the central crags sector of Hadrian's Wall, between Cawfields and Caw Gap in Northumberland. It is recorded in the Pleiades gazetteer of ancient places as a watch tower site from the Roman period in Britain.
Turret 41B (Thorny Doors) is classified as a Roman watch tower — a military site in the Pleiades ancient world gazetteer. Roman Britain's archaeology encompasses thousands of sites ranging from legionary fortresses and marching camps to villas, temples and towns.
Several Roman sites lie within a short distance, including Milecastle 42 (Cawfields) (0.5 km), Turret 41A (Caw Gap) (0.5 km), Milestone House Roman temporary camp and section of the Stanegate Roman road (0.6 km). Aubrey Research maps over 2,200 Roman sites across Britain, drawn from the Pleiades ancient world gazetteer.
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