a wall in northern England built between 122 and 127 AD by the Roman emperor Hadrian, from Wallsend on the River Tyne to Bowness on the Solway Firth . It was the northern border of the Roman Empire, from which the Romans could keep back the Picts . It was a major achievement, 73 miles (120 kilometres) long and 16 feet (4.9 metres) high, with forts (= strong military buildings for defence) every mile along its length. Long sections of the wall still remain, and thousands of tourists visit it every year. It was made a World Heritage Site in 1987.
See also Antonine Wall .