Hadrian's Wall Marks Neither England's Border Nor Rome's Edge

Hadrian's Wall is more than 1,900 years old and still a textbook case for studying a frontier between us and them — a formulation that works from both sides of a divide. It also confounds the tidy version of the story. The wall marks neither the English–Scottish border nor the furthest northern extent of Roman Britannia. A long stone barrier across northern England invites the assumption that it was the edge of the map, or at least the edge of the empire, and neither is right. That is part of what makes the wall useful as a case study: a frontier like this is defined by the relationship across it rather than by where the known world stops.