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Y Gaer Fawr, hillfort on Garn Goch or Carn Goch

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Map ReferenceSN62SE
Grid ReferenceSN6912024320
Unitary (Local) AuthorityCarmarthenshire
Old CountyCarmarthenshire

Y Gaer Fawr or Garn Goch hillfort is a very large stone-walled defended enclosure occupying a dramatic isolated ridge. The hillfort is owned and managed by the Brecon Beacons National Park Authority. Given the size and complexity of the hillfort a Late Bronze Age or Iron Age date is most likely for its main construction and development but it may incorporate earlier monuments. It is one of the largest hillforts in Wales, enclosing 16.6 hectares (the main hillfort plus its annexe) and is only surpassed in enclosed size in south Wales by the 22 hectare Deer Park coastal promontory fort in western Pembrokeshire; the larger 20.5 hectare Penycloddiau hillfort lies in northeast Wales on the Clwydian Range (see Lock and Ralston 2022).

The main hillfort is enclosed by around 1700 metres of rampart, although the annexe added to the north side gives an additional 700 metres of earth and stone-built rampart. The hillfort measures 720m from end to end, northeast to southwest, and 230m across at its widest point in the southwestern part of the fort. A widening of the rampart to the south at the southwestern end appears to have been designed to enclose a ‘lower annexe’ of more level ground in a more sheltered location below a line of cliffs.

A new survey of the fort was completed by A H A Hogg for the Royal Commission in the early 1970s (see Hogg 1974), with the drawn archaeological survey based upon specially-flown photogrammetric aerial photographs allowing contouring and the main features to be accurately located. More recently in 2019 a new drone-derived photogrammetric model of the fort was completed by Mark Walters for the Brecon Beacons National Park Authority.

The hillfort has at least eight entrances. There are the ruins of two prehistoric main gates: a pair of parallel slab-lined passages at the northeast end of the fort and the collapsed ruins of a walled and slab-lined gateway passage through the large scree mass of the southwestern rampart. The southwestern gateway is further elaborated by surviving sections of stepped drystone walling flanking its northern side and retaining the taller mass of the high scree rampart beyond. In addition to these two main gates there are currently six recorded postern gates through the side ramparts, although more may await discovery in a future survey. As with the main gateways, the method of construction of these side gates appears to have been using tall upright slabs, infilled with drystone walling. It is not clear whether all were roofed, but loose slabs in the northwest rampart posterns suggest collapsed capping stones. One of two postern gates in the southeast rampart is the best preserved on site, comprising a narrow passageway lined with tall stones and largely clear of rubble infill. National Park Archaeologist Alice Thorne has suggested the clarity of this gate passage may be related to its continued use in later centuries, as it lies close to the medieval farmstead established inside the fort (see below). At least four other gaps through the rampart were correctly described by Hogg as ‘modern’; however, the current entrance through the southwestern rampart while not prehistoric, is well constructed and may constitute a medieval or later gateway constructed for the farming use of the fort.

The hillfort encloses a great natural valley on a route up to higher ground from the floor of the River Tywi below. The hillfort interior contains a central pond and boggy area, with a number of rock outcrops. A slab outcrop in the eastern part of the fort may have provided some of the structural stones for the gateways. Otherwise the interior is largely empty of clearly identifiable prehistoric domestic buildings. A rock cut platform of one roundhouse can be seen in the southern centre of the fort close to the medieval farmstead. Just to its north (at SN 692 242) is a possible low standing stone around 1m tall identified by Toby Driver in September 2009. It may be that largescale geophysical survey would discover a range of more ephemeral timber-built buildings inside the fort, but these may only be discovered through detailed excavation. The medieval farmstead in the centre of the fort comprises the boulder-walled footings of a rectangular house and, to its north, a large 30-metre long barn. The size of the barn may imply the influence of a monastic estate.

One of the most enigmatic features of the fort, on the highest summit, is a stone long cairn some 55m long (NPRN 409533). Its appearance suggests a Neolithic date but no megalithic structures or remains of a burial chamber are currently visible. It may have been re-used in Bronze or Iron Age times. A pottery fragment, possibly wheel-turned, was found in the saddle west of the fort. It was later deposited at Derwydd Manor.

A smaller hillfort, Y Gaer Fach (NPRN 100872), of only 1.5ha, is sited some 180m to the west with Llwyndu Camp hillfort a further 600m west of Y Gaer Fach.



Driver, (in press). The Hillforts of Iron Age Wales. Logaston Press.

Laws in Archaeologia Cambrensis fifth series X (1893), 173-5
Evans in the Transactions of the Carmarthenshire Antiquarian Society Vol. V (1909-10), 84-5, 89-91, 100-102
Hogg, A. H. A. 1974. Carn Goch, Carmarthenshire. Archaeologia Cambrensis. Vol. CXXIII. Pp. 43-53.

Lock, G.R. and Ralston I. 2022. Atlas of the Hillforts of Britain and Ireland. Edinburgh University Press.

T. Driver, RCAHMW, 28th September 2009.

Updated by T. Driver, RCAHMW, 23rd November 2022, following joint Royal Commission and BBNPA site visit, 22/11/22.