Which Roman emperor built the defensive wall known as the Antonine Wall in Scotland?

Roman emperor Antoninus Pius built the Antonine Wall in Scotland.

Construction began around 142 CE under the governor Quintus Lollius Urbicus. The frontier ran across central Scotland between the Firth of Forth and the Firth of Clyde. Unlike Hadrian’s Wall, which was largely stone, the Antonine Wall consisted mainly of a turf rampart built on a stone foundation, with a deep defensive ditch on its northern side.

The wall included forts, fortlets, roads, and temporary camps for the soldiers who built and guarded it. It marked the northern frontier of the Roman province of Britannia for several decades, although Rome did not maintain it permanently.

Roman forces withdrew south to Hadrian’s Wall around 162 CE. The Antonine Wall was later reoccupied briefly during the reign of Septimius Severus, but it never replaced Hadrian’s Wall as the empire’s long-term northern frontier. The site is now part of a UNESCO World Heritage property.