England–Wales border point. In 926, Edward's successor Athelstan, "King of the English", summoned the Welsh kings including Hywel Dda of Deheubarth to a meeting at Hereford, and according to William of Malmesbury laid down the boundary between England and Wales, particularly the disputed southern stretch where he specified that the eastern bank of the Wye should form the boundary. By the mid-eleventh century, most of Wales had become united under the king of Gwynedd, Gruffudd ap Llywelyn. In 1055, he marched on Hereford and sacked the city. He also seized Morgannwg and the Kingdom of Gwent, together with substantial territories east of
Wye Valley well as in the adjoining Forest of Dean. The medieval boroughs of Goodrich and Chepstow, at each end of the Wye Gorge, may have originally been established at this time. Closely following the River Wye, Offa's Dyke was built in the 8th century under King Offa to mark out the boundary between England and Wales and is, today, the longest archaeological monument in Britain. Offa's Dyke Path long distance footpath today traces the route through the Wye valley on the English bank, while the Wye Valley Walk follows the Welsh bank. When the Normans conquered the region in the 11th