River Wye given a Latin name "Vaga", an adjective meaning 'wandering'. The Tithe map references a Vagas Field in both Whitchurch and Chepstow. Philologists such as Edward Lye and Joseph Bosworth in the 18th and early 19th centuries suggested an Old English derivation from "wæg", "wave". The source of the Wye is in the Welsh mountains at Plynlimon. It flows through or past several towns and villages including Rhayader, Builth Wells, Hay-on-Wye, Hereford (the only city on the River Wye), Ross-on-Wye, Symonds Yat, Monmouth and Tintern, meeting the Severn estuary just below Chepstow. Its total length is . The lower of the
England–Wales border Skenfrith (in Wales), towards Monmouth, looping eastwards to include the town itself and a surrounding area within Wales. At Redbrook, the boundary again reaches the Wye, and follows the river southwards, past Tintern and Chepstow on the Welsh side, to its confluence with the Severn at the Severn Bridge. The boundary then continues down the Severn estuary towards the Bristol Channel, with the small island of Flat Holm being administered as part of Wales and the neighbouring island of Steep Holm as part of England. The boundary passes between Flintshire, Wrexham County Borough, Powys, and Monmouthshire in Wales and Cheshire