Longest ancient Roman wall
Hadrian’s Wall
118 kilometre(s)
United Kingdom ()

The longest wall from the ancient Roman world that survives today is the 118-km (73-mile) Hadrian’s Wall project in the Roman province of Britannia (today the UK), much of which still runs from the Solway Firth in the east to the River Tyne in the west. Construction started in AD122–126 under the orders of Emperor Hadrian as a defensive and customs barrier. It was mostly made from stone, using the labour of Roman legionnaires to create a wall measuring 2.5–3 m (8–10 ft) wide and 4.5-6 m (15–20 ft) high. Milecastles at regular intervals housed up to 32 soldiers, while larger forts at approximately 5-mile intervals allowed traffic to pass between north and south. It was the largest structure ever built by the ancient Romans.

Also known as the the Roman Wall, Picts' Wall or Vallum Hadriani in Latin, Hadrian’s Wall was designated as a UNESCO World Heritage Site in 1987.