Llanthony is a village in the community of Crucorney on the northern edge of Monmouthshire, South East Wales, United Kingdom. Llanthony is located in the Vale of Ewyas, a deep and long valley with glacial origins within the Black Mountains, Wales, seven miles north of Abergavenny and within the eastern section of the Brecon Beacons National Park. The …Llanthony is a village in the community of Crucorney on the northern edge of Monmouthshire, South East Wales, United Kingdom. Llanthony is located in the Vale of Ewyas, a deep and long valley with glacial origins within the Black Mountains, Wales, seven miles north of Abergavenny and within the eastern section of the Brecon Beacons National Park. The village is on an unclassified road leading northwards from Llanvihangel Crucorney to Hay-on-Wye.