Mynydd Illtud

Mynydd Illtud is an extensive area of common land near Libanus, Powys, Wales, located in the Brecon Beacons National Park and some three miles south-west of Brecon [1]. The common is an undulating plateau lying between 330 and 370 metres above sea level [1]. Its highest points are 381 metres at Allt Lom and 367 metres at Twyn y Gaer trig point overlooking the valley of the River Usk [1]. Twyn y Gaer is the site of an Iron Age hill fort [1]. The Iron Age hillfort of Twyn y Gaer sits atop the grassy mound on the northern tip of the common [1]. Research by A. H. A. Hogg on this hill fort was published in 1982 [1]. The course of a Roman road, Sarn Helen can be traced from south-west to north-east across the common [1].