London Wall who overran Hadrian's Wall in the 180s. It may be linked to the political crisis that emerged in late 2nd century when the governor of Britain Clodius Albinus was consolidating his power after claiming the right of succession as Roman emperor. After a struggle with his rival, Septimius Severus, Albinus was defeated in 197 AD at the Battle of Lugdunum (near Lyon, France). The economic stimulus provided by the wall and Septimius's subsequent campaigns in Scotland improved Londinium's financial prosperity in the early 3rd century. The wall's gateways coincided with their alignment to the British network of Roman roads. The
Architecture of Scotland Trimontium, and a continuous fortification between the Firth of Forth and the Firth of Clyde known as the Antonine Wall, built in the second century AD. Beyond Roman influence, there is evidence of wheelhouses and underground souterrains. After the departure of the Romans there were a series of nucleated hill forts, often utilising major geographical features, as at Dunadd and Dunbarton. Castles arrived in Scotland with the introduction of feudalism in the twelfth century. Initially these were wooden motte-and-bailey constructions, but many were replaced by stone castles with a high curtain wall. In the late Middle Ages new castles were