The Romans built Hadrian's Wall in about AD122, defining the northernmost limit of the Roman Empire in Britain at that time. It ran 73 miles, coast to coast, and consisted of a stone built wall around seven metres high with a ditch to the north and a bigger bank and ditch earthwork (the Vallum) to the south. Turrets, milecastles, and forts were built at regular intervals. The course of the wall ran from Segedunum at Wallsend on the East Coast through Newcastle-upon-Tyne.