Royal Commission aerial reconnaissance on 10th July 2018, during the 2018 drought, recorded cropmarks of a substantial univallate defended enclosure partly underlying the present farm of Gaergywydd.
A hillfort or defended enclosure had long been suspected in this location, not only because of the 'gaer' element in the placename but because of the discovery of a large silted-up ditch to the west of and below the farm during pipeline excavations in 1986 by the Dyfed Archaeological Trust (PRN 13052). Ken Murphy noted: 'The ditch measured some 6m across and at least 2m deep. The projected edge indicadte a depth of some 4-5m. The ditch was running in an east-west direction. Its size indicates a defensive function and may be associated with the place-name of the farm of Gaergywydd immediately to the east. KM 1986'.
The 2018 aerial photographs show parchmarks of a curving single ditch extending south, then west of Gaergywydd, enclosing the steep hillslope below the farmhouse. This then returns north, and then angles sharply east for a return under the present farm yard - returning around SN 6284 8522. The whole describes a D-shaped defended enclosure measuring 160m north-south by 100m east-west approximately.
Image refs: AP_2018_4307-08
T. Driver, RCAHMW, Feb 2024