Y Gaer, Penrhyncoch is an oval univallate hillfort sited on the leading edge of a long, narrow east-west ridge which ascends to the east towards high ground. It overlooks the lowland valley of the Stewi and the Silo to the west, occupied by present-day Penrhyncoch village. Survey by the Ceredigion Archaeological Survey (published by 1988) showed the fort to measure about 100m x 60m internally, with the stony rampart surviving to about 1.5m high in places. The CAS note the possible survival of house platforms in the eastern part of the fort. Aerial photography under parched conditions has shown the clear gap of the plough-denuded entrance surviving on the west side of the fort, although the surface traces of the earthwork on the ground are indistinct. Inspection by the author has shown no traces of original revetment to survive in the rampart. The hillfort is named `Y Gaer' on the 1834 Ordnance Survey map.

The position of the hillfort on the ridge is interesting. It is sited at a break of slope on the leading edge of the ridge, so that its rampart forms a striking feature on the skyline when seen from the lowlands to the west; thus is exact position appears to have been a matter of design. If sited further west or east it would either have been rendered invisible from below, or indistinct on the hillslope below the horizon. The present-day ridge road runs close by the south side of the fort, and it may be that this ridge has long been a focus for east-west movement between lowland and upland since prehistory, thus placing the fort in a good position for communication and trade. Nineteenth century Ordnance Survey County Series mapping shows a spring immediately outside the south rampart of the hillfort; if active in prehistory this would have provided a ready source of water, but local rivers were also very close. Aerial photography by RCAHMW in 1995 discovered a nearby rectangular cropmark enclosure at Pantdrain (NPRN 301882). It is possible to postulate that this was a contemporary palisaded stock enclosure associated with the hillfort.

From: Driver, T., 2005 The Hillforts of North Ceredigion: Architecture, Landscape Setting and Cultural Contexts. Unpublished PhD thesis, The University of Wales, Lampeter, Department of Archaeology and Anthropology.