A large round cairn is located on the summit of Mynydd Machen at 362m above OD, a location with commanding views in all directions. The cairn is a turf-covered stony mound measuring 23m east by west by 21m on plan, 1.5m high on the east side, 1m high on the south-west side. The cairn is flat-topped though slightly dished around the base of the Ordnance Survey trig pillar that surmounts it. The cairn has suffered damage from off-road vehicles being driven onto it, especially on the east side.
Other sources:
OS 495 record card: ST29SW11.
RCAHMW air photos: AP94-CS 0596; AP945079/49.

David Leighton, RCAHMW, 24 March 2016