Sculpture in Scotland CE, building a series of forts, but by 87 CE the occupation was limited to the Southern Uplands and by the end of the first century the northern extent of Roman occupation was a line drawn between the Tyne and Solway Firth. The Romans eventually withdrew to a line in what is now northern England, building the fortification known as Hadrian's Wall from coast to coast. Around 141 CE they undertook a reoccupation of southern Scotland, moving up to construct a new "limes" between the Firth of Forth and the Firth of Clyde, where they built the fortification known as
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