1. Few Welsh prehistoric sites capture the imagination as powerfully as Tre'r Ceiri hillfort which dominates the Llyn Peninsula from the easternmost summit of the three-peaks of Yr Eifl. Looking down from a scree-strewn summit at a height of 485m O.D., Tre'r Ceiri is one of the best preserved Iron Age hillforts in Britain where round houses, gateways and ramparts can be seen in a remarkably intact condition.

Tre'r Ceiri occupies a steeply-sloping site whose summit is occupied by a substantial Early Bronze Age burial cairn, clearly preserved and respected within the later hillfort. The main hillfort is enclosed by a formidable single rampart which still stands up to 3.5m high in places. Where nearly intact, the top of the rampart still has its parapet walk reached via a number of sloping ramps from the interior. This wall is broken by two main gateways, both of which funnelled visitors through narrow, restrictive passages, as well as three `posterns' or minor gateways, one of which at least was designed to allow inhabitants out down a narrow mountain path to gather water from a spring. Beyond the main hillfort is a second partial outer wall, reinforcing more vulnerable approaches on the north and west sides. This too is broken by an outer gateway which overlies an earlier approach track to the hillfort, probably indicating that this outer defence was a secondary work.

As befits one of Britain's finest hillforts there have been many visits to, and surveys and excavations of, Tre'r Ceiri over the centuries. During the 1950s, A H A Hogg and officers from the Royal Commission conducted several campaigns of excavation and survey at the Caernarfonshire hillforts to clarify their development for the (then) forthcoming three volumes of the Caernarvonshire Inventory. Together with W E Griffiths, Hogg completed a full survey of Tre'r Ceiri in 1956, complete with contours and details of surrounding hillslope enclosures, building upon Harold Hughes's pioneering measured survey of 1906. This was immensely detailed, yet clear, and was only superseded by a modern total-station survey of 1980. We know from excavations, by Hogg and others, that the hillfort was probably constructed in the later Iron Age and remained in use until at least the 4th century AD, the late Roman period. Other prominent stone-built hillforts on Llyn, principally Garn Boduan and Carn Fadrun, have very late-phase stone citadels on their highest summits which are thought to have been castles of medieval Welsh princes; Tre'r Ceiri lacks any similar evidence.

In 1989, Cyngor Dosbarth Dwyfor and Gwynedd County Council, with funding from Cadw, began a long programme of consolidation and repair of the fort with archaeological supervision provided by the Gwynedd Archaeological Trust. The project ran for a decade, often through the most adverse of weather conditions, leaving this most intriguing of hillforts renewed and ready to endure another two thousand years of life.

Sources: Baring-Gould and Burnard in Archaeologia Cambrensis IV (1904), 1-16
Hughes in Archaeologia Cambrensis VII (1907), 38-2
Hogg in Archaeological Journal 117 (1960), 1-39
RCAHMW Caernarvonshire Inventory II (1960), 101-3

For more recent excavation & restoration see: Archaeology in Wales 31 (1991), 16; 32 (1992), 57; 33 (1993), 49-50; 34 (1994), 46-7; 38 (1998), 98.

T. Driver, RCAHMW, 6th Aug 2008

2. Extract from Driver, T. 2023. The Hillforts of Iron Age Wales. Logaston Press. Pp. 254-8

‘Crowning a high, rocky summit at the northern end of the Llŷn Peninsula in Gwynedd is one of the most unusual and special hillforts in the whole of southern Britain. The three peaks of Yr Eifl, incorrectly in English ‘The Rivals’, form a striking three-pronged skyline feature visible for miles around..  Only on the steeply-sloping southern peak, at 480 metres above sea level, do we find signs of permanent settlement in the form of Tre’r Ceiri. This was a long-lived stone-walled hillfort dating from Iron Age and Roman times with sporadic occupation likely to have extended into the early medieval period.  

Although proclaimed in books and on visitor signs as ‘The Town of the Giants’, based on a  reading of its current name thought to have derived from the plural of ‘cawr’ for giant, its original name Tre‘r Caeri meant ‘Town of the Fortresses’. In the eighteenth century Thomas Pennant described it as ‘… the most perfect and magnificent, as well as the most artfully constructed British post I ever beheld.’ In 1960 the hillfort archaeologist A H A Hogg wrote that; ‘In its present form the fortress is probably unique’.   

… The interior of Tre’r Ceiri is crowded with some 158 huts and other structures, the earliest of which appear to be the roundhouses which contained almost exclusively prehistoric finds. Further analysis of the chronology of the structures shows that 62% of the partitioned D-shaped buildings contained Romano-British pottery. House 23, a rectangular building, produced a bone comb of late Roman or early medieval character.

… In 1903 Reverend Baring-Gould and Robert Burnard, fresh from their early excavations in Pembrokeshire, cleared 32 of the ‘cyttiau’ or huts inside the fort. Three years later Harold Hughes of the Cambrian Archaeological Association returned to the hilltop to excavate another 32 structures assisted by workmen who; ‘...laid bare walls and doorways, and enabled the outlines of many cyttiau’ to be followed accurately...’ . Both seasons of work produced a range of pottery, stone, bone and metal finds from the houses mostly dated from 150 BC to AD 400.  

Later, during the 1950s, the Royal Commission conducted further campaigns of excavation and survey to clarify the development of the fort towards the publication of a definitive account for the 1960 Caernarvonshire Inventory. Finally, following more than a century of conservation concerns over the condition of the tumbled houses and ramparts, Gwynedd County Council began a programme of excavation and repair to the walls in 1989 supervised by the Gwynedd Archaeological Trust. It is this programme of work we have to thank for the current clarity of the remains. Modern rebuilds are clearly marked with drill-holes showing replaced stones.  

The main hillfort forms an elongated oval enclosure built on a sloping site, measuring some 290m northeast-southwest by 100 metres containing around 150 houses and huts. Originally the stone-walled ramparts stood with a rear foundation footing, a wall-walk accessed here and there by internal steps and a low parapet wall…

At the eastern summit is a great Bronze Age burial cairn, respected during the lifetime of the fort and perhaps re-used for Iron Age burials. The main fort encloses a modest 2.1 hectares, but the settlement was enlarged to 3.1 hectares overall with the addition of an annexe on the north and west sides…

There were two main gateways: on the northwest, inner and outer gateways gave access up through the annexe into the main hillfort via a zig-zag path. This path not only served to negotiate the steep slopes but would have slowed down any attackers, exposing them side-on to a hail of sling shot and spears from above. Today these northwest gates have been restored as stone-lined passageways to walk through, having previously been blocked by collapsed rubble prior to the start of conservation work in 1993. The other main gate at the southwest point commanded spectacular views across the Llŷn Peninsula but the entrance passage and walls are low and partly obscured by tumbled stone.  

There are a handful of smaller postern gateways, as with Garn Goch. The best-preserved example towards the summit of the fort was re-roofed in the recent works..

Inside the hillfort we see one of the most clearly visible Iron Age and Roman villages in Britain. Tre’r Ceiri remains an arresting hillfort to visit, almost a ‘Welsh Pompeii’ considering its levels of preservation. Yet the crowded housing here is unusual. The early Iron Age roundhouses were later subdivided in Romano-British times and later added to again with clusters of D-shaped buildings and crude shelters. At least one house, hut 41 against the southern rampart, may have been used for burial suggested by the unusual find of a beaded collar from the building; such finds usually accompany Iron Age and Roman burials. A further example is recorded from nearby Clynnog…’

Updated by Dr Toby Driver, Royal Commission, January 2005