The Antonine Wall, known to the Romans as Vallum Antonini, was a turf fortification on stone foundations, built by the Romans across what is now the Central Belt of Scotland, between the Firth of Forth and the Firth of Clyde. Built some twenty years after Hadrian's Wall to the south, and intended to supersede it, while it was garrisoned it was the northernmost frontier barrier of the Roman Empire. It spanned approximately 63 kilometres (39 miles) and was about 3 metres (10 feet) high and 5 metres (16 feet) wide. Lidar scans have been carried out to establish the length of the wall and the Roman distance units used. Security was bolstered by a deep ditch on the northern side. It is thought that there was a wooden palisade on top of the turf. The barrier was the second of two "great walls" created by the Romans in Great Britain in the second century CE. Its ruins are less evident than those of the better-known and longer Hadrian's Wall to the south, primarily because the turf and wood wall has largely weathered away, unlike its stone-built southern predecessor.

The Antonine Wall had a variety of purposes. It provided a defensive line against the Caledonians. It cut off the Maeatae from their Caledonian allies and created a buffer zone north of Hadrian's Wall. It also facilitated troop movements between east and west, but its main purpose may not have been primarily military. It enabled Rome to control and tax trade and may have prevented potentially disloyal new subjects of Roman rule from communicating with their independent brethren to the north and coordinating revolts. Urbicus achieved an impressive series of military successes, but like Agricola's they were short-lived. Construction began in 142 CE at the order of Roman Emperor Antoninus Pius, and took about 12 years to complete. Having taken twelve years to build, the wall was overrun and abandoned soon after CE 160. The wall was abandoned only eight years after completion, and the garrisons relocated rearward to Hadrian's Wall.

Pressure from the Caledonians may have led Antoninus to send the empire's troops farther north. The Antonine Wall was protected by 16 forts with small fortlets between them; troop movement was facilitated by a road linking all the sites known as the Military Way. The soldiers who built the wall commemorated the construction and their struggles with the Caledonians with decorative slabs, twenty of which survive.