 Fragments of Hadrian's Wall are visible in parts of Newcastle, particularly along the West Road.The course of the "Roman Wall" can be traced eastwards to the Segedunum Roman fort in Wallsend—the "wall's end"—and to the supply fort Arbeia in South Shields.The extent of Hadrian's Wall was , spanning the width of Britain; the Wall incorporated the Vallum, a large rearward ditch with parallel mounds, and was built primarily for defence, to prevent unwanted immigration and the incursion of Pictish tribes from the north, not as a fighting line for a major invasion.