There are two large carneddau on the Carno mountain, where a sanguinary battle was fought between Ethelbald King of Mercia and Roderic Molwynog, a prince of North Wales, in which the latter is said to have been victorious. This bit of legend is offered in 'A topographical dictionary of Wales v1' by Samuel Lewis (1833).
Cave in cliffs on the northern slopes of Twr Pen-cyrn, with evidence of possible paleolithic use. Info from Coflein:
Eight bones apparently associated with 2 large fragments of antler excavated from the cave by J. Ellwood in 1818. All upper palaeolithic in form and possibly indicating a settlement site. There has been some damage by cavers. Notes from an Ordnance Survey record card, 1980.