Architecture of Scotland in the Roman era England. Around 141 CE they moved up to construct a new "limes", a sward-covered wall made of turf known as the Antonine Wall, the largest Roman structure in modern Scotland. They soon retreated to Hadrian's Wall, with occasional expeditions that involved the building and reoccupation of forts, until the collapse of Roman power in the early fifth century. Caledonia was the name that the Romans gave to the land north of their province of Britannia. In his "Geographia", Ptolemy, possibly drawing on earlier sources of information as well as more contemporary accounts from the Agricolan invasion, identified 19 "towns" in
Scotland during the Roman Empire as unified ideas until centuries later. In fact, the Roman Empire influenced every part of Scotland during the period: by the time of the Roman withdrawal from Britain around 410, the various Iron Age tribes native to the area had united as, or fallen under the control of, the Picts, while the southern half of the country was overrun by tribes of Romanized Britons. The Scoti (Gaelic Irish raiders) who would give Scotland its English name, had begun to settle along the west coast. All three groups may have been involved in the Great Conspiracy that overran Roman Britain in