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
The Kymin 2015. The Kymin The Kymin, (), is a hill overlooking Monmouth, in Monmouthshire, Wales. It is located approximately one mile east of Monmouth, on the eastern side of the River Wye and adjacent to the border with the Forest of Dean and England. The summit of the hill, about 800 feet above sea level, is known for its neo-classical monuments, the Roundhouse and the Naval Temple, built between 1794 and 1800. The site is a designated Area of Outstanding Natural Beauty (AONB) and is owned by the National Trust for Places of Historic Interest or Natural Beauty. The Roundhouse was