Offa's Dyke is a man made border line roughly between England and Wales. It was created in the later half of the 8th century as a separation of the English kingdom of Mercia and the Welsh peoples. It is the work of King of Mercia, Offa. Like Hadrian's Wall, it is believed that the dyke was constructed not only as a defensive barrier by the Anglo-Saxons, but as a political statement of power.
Many historians regard Offa as the most powerful Anglo-Saxon king before Alfred the Great, however there are mixed feelings. Offa was a protector of the church, which he encouraged as a source of stability and education by supporting it with grants of land and building abbeys. Some believe he was part of the process leading to a unified England, while others believe that he just had a lust for power.
Offa was frequently in conflict with various Welsh kingdoms and he is recorded as campaigning against them in 778, 784 and 796.
The dyke stretches as wide as 65 feet and eight feet tall. The dyke constantly provides an open view from Mercia into Wales. It is not continuous and is built where natural barriers did not already exist, although the gaps in the dyke have been debated.
Some historians believe the dyke at once went from "sea to sea" as Asser, 9th and 10th century writer, had recorded. This would have been over 150 miles. Others believe that there is only evidence of the trail extending 64 miles. Regardless of the length, the dyke is regarded as the largest and most recent great construction of the preliterate inhabitants of Britain.
The Offa's Dyke Association maintains the Offa's Dyke Path. The trail follows most of the route of the dyke, almost 176 miles, and is a designated British National Trail.