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Castell Henllys Hillfort

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Map ReferenceSN13NW
Grid ReferenceSN1172039050
Unitary (Local) AuthorityPembrokeshire
Old CountyPembrokeshire
PeriodIron Age
1. A settlement enclosure, about 88m north-west to south-east by 74m, occupying an inland promontory, defined on the open, north-west side by a double rampart and ditch, with an annex beyond; occupation within the enclosure ceased, about 0BC/AD, when a settlement was established in the annex, there being a possible reoccupation of the enclosure in the late/post Roman period.
A continuing program of excavation (Mytum, various reports in AW, esp. 1989; 1996; 2002; also Mytum 1999a) has been accompanied by reconstruction of structures within the enclosure (Mytum 1986). The site is currently use for educational purposes (Mytum 1999b).

Sources: Mytum 1986 (BBCS 33), 283-90;
1989 (AW 29), 6-10;
1996 (AW 36), 3-10;
1999a (Curr. Arch. 161), 164-72;
1999b (in Stone & Planel (eds.) 'The Constructed Past'), 181-93;
2002 (AW 42), 110-112, 119, 151.
J.Wiles 05.09.2003

2. Castell Henllys has been the focus of scientific excavations since 1980 which have provided an unparalleled understanding of a small promontory fort occupied from Iron Age to Roman times. These excavations have also informed a long-term exercise in `experimental archaeology?, in which Iron Age houses and other buildings have been reconstructed on their original foundations using prehistoric building materials and techniques. The first report of the excavations was published by Professor Harold Mytum in 2013.

Castell Henllys (the name implies an `old palace? or early medieval court) was originally purchased privately with the intention of turning the fort into a tourist attraction as work progressed. In time the site was bought by the Pembrokeshire Coast National Park Authority and now functions as an exemplary centre for education, interpretation and archaeological training in west Wales, with annual projects run by Cambria Archaeology and the University of York. Despite its relatively small size, the history of Castell Henllys has proved to be anything but simple. The main gateway was begun in the fifth century BC and started as a long stone-walled passageway flanked by pairs of massive timber posts supporting a large gate and, probably, a bridge or tower over the entrance. Two pairs of guard chambers, semi-circular rooms where the gatekeepers could shelter and inspect visitors, were recessed into the sides of the passage. The excavators felt that this specialised gateway was built not by the inhabitants of the fort, but by visiting artisans who had the knowledge and expertise to undertake such a complicated piece of building. The gateway was rebuilt several times during the occupation of the fort, and there were episodes when it was on the point of collapse, or even burnt down. Outside the main fort was a further set of defences. Early on these included a chevaux-de-frise, a curtain of sharp, upright stones similar to that at nearby Carn Alw in Mynydd Preseli. It may originally have been far more extensive, but later, around 300 BC, the chevaux-de-frise was replaced by a substantial bank and ditch and only survives today where this later bank covered it. Excavations at Castell Henllys also uncovered a cache of several thousand sling stones stored behind the rampart. These were a common weapon on Iron Age hillforts, and an experienced slinger could kill or injure a victim at a distance of 60 metres or more.

Inside Castell Henllys stand reconstructed round houses in their original positions. These conical thatched buildings represent carefully-considered experiments in archaeology, rebuilt from the patterns of postholes and wall-trenches discovered on site. Such substantial buildings required large quantities of raw material. Bennett has documented the 30 coppiced oak trees, 90 coppiced hazel bushes, two thousand bundles of water reed and two miles of hemp rope and twine consumed in the construction of the largest round house alone, forming its rafters, posts, ring-beams and wattle walls. After the fort was abandoned in the late Iron Age, a small but well-off Romano-British farmstead was established just outside. A later refortification of the fort may suggest occupation by Irish settlers in the post-Roman period, but after this Castell Henllys became lost and overgrown until it was surveyed and named on a late-eighteenth-century estate map.

Text edited from T. Driver, 2006, Pembrokeshire, Historic Landscapes from the Air, 2006.


Driver, T. 2016. The Hillforts of Cardigan Bay. Logaston Press.

Mytum, H. 2013. Monumentality in Later Prehistory, Building and rebuilding Castell Henllys. Springer.
application/pdfAENT - Archaeological Reports/Evaluations (non Trust)