Llanrhaeadr-ym-Mochnant is a village and community in Powys, Wales; about 9 miles west of Oswestry and 12 miles south of Llangollen, on the B4580 road. It lies near the foothills of the Berwyn mountains on the river Rhaeadr. At the top end of the valley is the Pistyll Rhaeadr waterfall, one of the traditional Seven Wonders of Wales. One mile north of the village is the hill Moel Hen-fache. The community includes the hamlet of Llanarmon Mynydd Mawr.