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
Wye Valley in the area of Symonds Yat and Slaughter Stream Cave near Berry Hill. At St Arvans, near Chepstow, the underground watercourses have carved out long cave systems, which exit at Otter Hole at the base of Piercefield cliffsthe only cave system in England or Wales which can only be reached through a tidal sump, making it a mecca for experienced cavers. Lancaut and Ban-y-Gor are Gloucestershire Wildlife Trust nature reserves. They both have SSSI status being part of the nationally important Lower Wye Gorge SSSI and within the Wye Valley AONB. The Wye Valley is important for its rich wildlife