Tre’r Ceiri and the stone forts of Llŷn

Few Welsh prehistoric sites capture the imagination as powerfully as Tre’r Ceiri hillfort which dominates the Llŷn Peninsula. 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.

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Interior view looking southwest in Tre' ceiri

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A unique fortress


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. 

Surveys and excavations


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’ 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 This was immensely detailed, yet clear, and was only superseded by a modern total-station survey of 1980.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 Llŷn, 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.

2,000 years of weathering


These stone ruins have long astounded visitors over the centuries and they are no less impressive today, yet two thousand years of weathering and collapse, together with pressure from visitors, has taken its toll on Tre’r Ceiri. As far back as 1894, members of the Cambrian Archaeological Association lamented its condition and lack of protection:

‘It would hardly be thought that in a civilised community it was possible that such a splendid specimen of a prehistoric city would be allowed to perish miserably… Yet stone by stone Treceiri is being gradually destroyed.’ (Archaeologia Cambrensis Vol. XII Fifth Series, 1895, 147)

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. 



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