Hadrian's Wall is a defensive fortification built by the Romans in the 2nd century AD. It stretched approximately 73 miles across northern England, marking the northern boundary of the Roman Empire. Constructed under the orders of Emperor Hadrian, the wall was made of stone and turf, featuring forts, watch towers, and gates. The wall served both military and administrative purposes, helping to control trade and immigration. It was manned by Roman soldiers and provided protection against tribes from the north. Today, Hadrian's Wall is a UNESCO World Heritage Site, attracting visitors interested in Roman history and archaeology.