The Roman Emperor known for his wall across northern Britain is Hadrian. Hadrian's Wall, constructed around AD 122, marked the northern limit of the Roman Empire in Britain and served multiple purposes, including defense against invading tribes and control of trade and migration across the border. The wall stretched approximately 73 miles and included forts, watch towers, and barriers. Hadrian's initiative to build this imposing structure reflected both the strategic military concerns of the empire and Hadrian's interest in fortifying and maintaining Roman culture in the provinces far from Rome.