England–Wales border after Harold's death at the Battle of Hastings, Wales was again divided without a leader to resist the Normans. Immediately after the Norman conquest of England, King William installed one of his most trusted confidants, William FitzOsbern, as Earl of Hereford. By 1071 he had started the building of Chepstow Castle, the first castle in Britain built of stone, near the mouth of the Wye. It served as a base from which the Normans continued to expand westward into south Wales, establishing a castle at Caerleon and extinguishing the Welsh kingdom of Gwent. William also installed Roger de Montgomerie at
Wye Valley Walk Hafren, having passed within viewing distance of the source of the River Wye on Plynlimon near Aberystwyth, a total of . The Wye Valley Walk is marked out by circular yellow waymark arrows, finger posts, and signs showing the path's logo, a leaping salmon. Most of the route follows Public Rights of Way. Some parts are permissive paths where owners have agreed for them to be used. Parts of Plynlimon are open countryside in which there is a right to roam established by the Countryside and Rights of Way Act 2000. The route passes through Chepstow, the Wye Valley AONB,