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
Wales 1536 formed a linear border stretching from the mouth of the Dee to the mouth of the Wye. Even after the Act of Union, many of the borders remained vague and moveable until the Welsh Sunday Closing act of 1881, which forced local businesses to decide which country they fell within to accept either the Welsh or English law. The "Seven Wonders of Wales" is a list in doggerel verse of seven geographic and cultural landmarks in Wales probably composed in the late 18th century under the influence of tourism from England. All the "wonders" are in north Wales: Snowdon