Suprisingly, the "axe head" sections each on one side of the circular top and bottom openings are unnessecary to the functioning, and just there for show.
It's also near a fort on the Antonine Wall, a further-north version of Hadrian's wall- so it's been the shortest route across Britain for quite a long time...
It's also near a fort on the Antonine Wall, a further-north version of Hadrian's wall- so it's been the shortest route across Britain for quite a long time...