30. What is the Intermediate Wall?

Traditionally, the Intermediate Gauge has been identified as the Hadrian’s Wall curtain wall constructed between Milecastle 54 and Bowness fort to replace the Turf Wall, after the abandonment of the Antonine Wall. It was built on a foundation of flagstones and was around 2.45m wide.

Further reading: Breeze 2006; Symonds and Mason 2009