Broad Wall
From Wikipedia, the free encyclopedia
Hadrian's Wall was built with two principal types of stone curtain wall. The earliest was the Broad Wall (or 'broad gauge') of around 3m in width and the later was the Narrow Wall (or 'narrow gauge') of 2.4m (but sometimes as little as 1.8m). Construction of the curtain wall progressed from east to west and had apparently reached the North Tyne by the time the decision was made to switch to the narrower gauge. However, Broad Wall foundations had already been laid as far as the river Irthing, where the Turf Wall began, and many turrets and milecastles were optimistically provided with stub 'wing walls' in preparation for joining to the Broad Wall.
The Broad Wall was initially built with a clay-bonded rubble core and mortared dressed rubble facing stones, but this seems to have made it vulnerable to collapse and repair with a mortared core was sometimes necessary.
