Radnor Forest (Welsh: Fforest Clud) is a rock dome composed of Silurian shales, mudstones and limestone in the historic county of Radnorshire, Powys, Mid Wales.
A similar plateau adjoining to the east, Black Mixen is the only Nuttall to have a communications mast (a radio transmitter) on its summit.
Mixed with these dwarf shrubs are hare's-tail cottongrass, purple moor-grass, sedges such as Carex binervis and a number of mosses and lichens.
The dwarf shrubs are very well grown and suggest the area has suffered little from fires in the recent past and that grazing pressures are light.
The steep-sided dingles and rock outcrops of the Forest's edge support rich plant communities, since these eastern Silurian shales are slightly calcareous.
Mossy saxifrage and rock stonecrop are common on some cliff faces, with marjoram and a number of interesting mosses and liverworts.
The forest was exploited as a military training area during the Second World War, and has remnants of such activity such as bomb craters and slit trenches.
Beyond the exclusion zone, further land to the west of Black Brook is subject to restricted access due to the presence of unexploded ordnance.
According to a legend, the local people built four churches in a circle around the Radnor Forest in order to contain the last dragon in Wales, who lay sleeping in the area.