Offa’s Dyke is a large linear earthwork that roughly follows the current border between England and Wales. The structure is named after Offa, the Anglo Saxon King of Mercia from AD 757 until 796, who is traditionally believed to have ordered its construction. Although its precise original purpose is debated, it delineated the border between Anglian Mercia and the Welsh Kingdom of Powys.
The Dyke, which was up to 65 feet (20 m) wide (including its flanking ditch) and 8 feet (2.4 m) high, traversed low ground, hills and rivers. Today the earthwork is protected as a scheduled monument. Some of its route is followed by the Offa’s Dyke Path; a 176-mile (283 km) footpath that runs between Liverpool Bay in the north and the Severn Estuary in the south.
Although historians often overlook Offa’s reign due to limitations in source material, he ranks as one of the greatest Anglo-Saxon rulers – as evidenced in his ability to raise the workforce and resources required to construct Offa’s Dyke. The construction of the earthwork probably involved a corvée system requiring vassals to build certain lengths of the earthwork for Offa in addition to the normal services that they provided to their King.