Scotland during the Roman Empire remains of a defensive line made of turf circa 7 metres (20 ft) high, with nineteen forts. It was constructed after 139 and extended for . It was possibly after the defences were finished that Urbicus turned his attention upon the fourth lowland Scottish tribe, the Novantae who inhabited the Dumfries and Galloway peninsula. The main lowland tribes, sandwiched as they were between Hadrian's Wall of stone to the south and the new turf wall to the north, later formed a confederation against Roman rule, collectively known as the Maeatae. The Antonine Wall had a variety of purposes. It provided
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