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 367. The era saw the emergence of the earliest historical accounts of the natives. The most enduring legacies of Rome, however, were Christianity and literacy, both of which arrived indirectly via Irish missionaries. Scotland had been inhabited for thousands of years before the Romans arrived. However, it is only during the Greco-Roman period that Scotland is recorded in writing. The work "On the Cosmos" by Aristotle or Pseudo-Aristotle mentions two "very large" islands called Albion (Great Britain) and Ierne (Ireland). The Greek explorer and geographer Pytheas visited Britain sometime between 322 and 285 and may have circumnavigated the mainland, which