Rhobell Fawr is the site of an ancient volcano that was active during the Early Ordovician period in the Arenig range within the Snowdonia National Park. Despite its modest height of 734 m (2,408 feet), it is a mountain with views of higher peaks all around, including the north face of Cadair Idris and distant Snowdon. The paths are not well trodden, but there is a distinct path up from Bwlch Goriwared, a couple of miles north-north-east of the small village of Llanfachreth.