The only known stone circle in Herefordshire, it is only just in the county - a few metres west and it would be in Wales. The monuments are on a summit of the Black Mountains, 560m above sea-level.
From "Prehistoric Sites of Herefordshire" - George Children and George Nash (1994 Logaston Press:
"From these two monuments are outstanding views across the whole of Herefordshire. The Malverns can be seen 50km to the east. Directly below lies the Olchon Valley where, in the 1930s, two Bronze Age burial cists were discovered. The cist burials and cairn and stone circle on the Black Mountains are, in our opinion, directly related.
The cairn and stone circle are approximately 30m from the Welsh border and Offa's Dyke Path. The centre of the cairn has, in the past, been excavated and therefore is recognisable by its doughnut shape. Small stones and locally quarried rock are clearly visible around the sides of the cairn, The stone circle is at present covered by undergrowth, and lies approximately 10m from the cairn. Use of the track that separates both monuments has eroded away the topsoil to reveal an ancient (Bronze Age and earlier) surface. Very little information exists about either of these monuments."
Edit November 2011: Having walked along the ridge, it is apparent that the cairn is in fact Wiral cairn, and that the grid reference given in the book is therefore incorrect.