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 fortification built across the width of what is now northern England. The wall was 80 Roman miles (73.5 statute miles or 117 kilometres) long, its width and height dependent on the construction materials which were available nearby. East of the River Irthing the wall was made from squared stone and measured 3 metres (9.7 ft) wide and 5–6 metres (16–20 ft) high, while west of the river the wall was originally made from turf and measured 6 metres (20 ft) wide and 3.5 metres (11.5 ft) high; it was subsequently rebuilt in stone. The wall was augmented by various ditches,