Hay-on-Wye the north-easternmost tip of the Brecon Beacons National Park, just north of the Black Mountains. The town is just on the Welsh side of the border with Herefordshire, England, here defined by the Dulas Brook. Where the brook joins the River Wye just north of the town, the border continues northwards along the river. The Wye was the boundary between the former counties and districts of Radnorshire and Brecknockshire. The adjacent village of Cusop lies on the English side of the Dulas Brook. The nearest city is Hereford, county town of Herefordshire, some to the east. The Royal Mail depot
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