By about AD 105, the Romans pulled out of Pictish Caledonia (Scotland). The border of Britannia was set between Coria (Corbridge) and Luguvalium (Carlisle). In AD 122, the Emperor Hadrian visited Britain and decided to build a big wall of stone with deep ditches along the border at this point. It was called Hadrian's Wall. The western part was wooden at first. It was 117km long, 4.5m tall and between 1.75 & 3m thick. It went both up over craggy mountains and down through flat valleys. It would keep the Picts out of Britannia. In the AD 140s, the Emperor Antoninus Pius sent his armies back into Caledonia. They built a 2nd wooden wall with big earth banks between the River Clyde and Forth. It was called the Antonine Wall; but they only stayed 20 years. Then Hadrian's Wall became the border again. Hadrian's Wall was built by the legions. It was garrisoned by auxiliary units. The numbers of soldiers on the Wall fluctuated (went up and down) over the years. The soldiers lived in forts, milecastles and turrets built along the Wall. In the late 4th century, a Roman commander in Britain called Magnus Maximus thought he should be Emperor. So he took a lot of the soldiers from the Wall to Europe to help him. After that, local soldiers tried to protect it, led by tribal warlords. The Wall fell into disrepair though and there were many attacks by the Picts.