This is the border country and the remains of an impressive bank and ditch, which once defined much of the boundary between what we now call England and Wales, runs south of Monmouth on high ground looking over the river towards Wales. This ancient earthwork was built by Offa, ruler of the Anglo-Saxon kingdom of Mercia from 757 – 796 AD and more or less follows the present-day boundary between England and Wales from the Severn at Chepstow to Prestatyn in North Wales. It is made up of a ditch and rampart. The ditch was built facing (what is today) Wales, probably to create an open view into Wales. It was about 27 metres wide and 8 metres high from the ditch bottom to the bank top. The dyke would have been a symbol of King Offa’s power and authority, as well as a formidable obstacle to any invaders. It was designed to impress, with the surrounding trees cleared to ensure the dyke was highly visible in the landscape. We don’t know if it was a defensive structure, in response to border threats from the Prince of Powys, or if it was an agreed boundary. Either way, it seems to have been abandoned fairly quickly, but it has had a lasting impact on the way people living either side of it define their cultural identity, especially contributing to a sense of common unity among the people living to the west of it in Wales.
You can see parts of the Dyke along the Offa’s Dyke National Trail in the Wye Valley National Landscape, where you can get a feel for its original impressive dimensions. The structure is visible where the path passes through Highbury Wood and Cadora Wood (between Bigsweir and Redbrook) and in Worgan’s Wood near Devil’s Pulpit, above Tintern.