An abridged version of this article was published in 'The Archaeologist' November 2001

After viewing the exploits of seventeen volunteers vainly attempting to survive the Iron Age against a superbly convincing backdrop for a recent TV series many wanted to know more about the site itself, especially the techniques that were being tried and the philosophy that underlay its approach. Here Phil Bennett takes us behind the scenes to see just how and why the Iron Age is being reconstructed in the Welsh countryside.

Prior to its purchase by the National Park the site was owned by Hugh Foster, an entrepreneur interested in the Iron Age who set up the site as a commercial visitor attraction. In 1981 the excavation of Castell Henllys began and Foster started to reconstruct buildings using the archaeological evidence provided by the dig. In 1991 Foster sadly passed away and the future of the excavation and the reconstructed buildings was in some doubt. The National Park, then a department of Dyfed County Council was able to gain funding from Cadw: Welsh Historic Monuments, the Countryside Council for Wales and the County Council itself to purchase the site. The National Park was keen to protect the site from inappropriate development and interpret it to visitors and to realise the vast educational potential for school children and students. In doing this the National Park was able to ensure the continuation of the archaeological investigation which had by that time been underway every year for a decade.

The site is the focus of a long-term archaeological excavation hosted by the National Park and organised and directed by the University of York with the with day to day practical co-direction of the excavation supplied by Cambria Archaeology. The National Park Authority provides support and funding for the project and for the last five years the annual grant has been provided solely for post-excavation work.

Interpreting archaeological heritage to the public can be problematic especially where little or no trace of that heritage is visible in the landscape. Even when archaeological features do survive, they can often be difficult to interpret. Castell Henllys Iron Age Fort is a good example of how the National Park overcomes these problems.

The principal aim at Castell Henllys is to interpret the archaeological resource to visitors and school children in an effective and engaging way. Wherever possible direct information gained from the excavation is used to interpret the site to visitors and a wide range of published sources are used when site specific material is not available.

Visitors approach the fort through woodland with atmospheric sculpture trails and small fields and paddocks containing breeds of sheep, cattle and pigs similar to those of the Iron Age. Close to the fort a field is given over to the production of Iron Age crops such as spelt wheat, celtic beans and woad, and a reconstructed ard is used for ploughing demonstrations. A more formal garden displays a range of the herbs and plants used in the Iron Age and Roman period.

Inside the fort

Four roundhouses and one four-poster store have been reconstructed at Castell Henllys. Their names reflect the way in which they are interpreted; the Chieftain's House, the Smithy and the Granary, or special features such as the Earthwatch roundhouse named after the foundation that part funded its construction. The Old Roundhouse was the first to be reconstructed at Castell Henllys, and is now the longest standing reconstructed Iron Age roundhouse in Britain.

The walls of the buildings were built with hazel rods woven around stakes and subsequently plastered with daub (a mixture primarily made up of clay, soil, dung, water and a fibrous material such as hay). The roofs are conical and constructed with straight rafters either spanning the entire pitch of the roof from the wall to the apex or utilising mid-roof and upper ring beams to facilitate the rafters and to brace the roof against its own weight and the effects of weather. The buildings are thatched with water reed.

The four-poster and the roundhouses have been reconstructed on their original, excavated foundations enhancing the sense of place generated by standing within the buildings. Visitors step over the threshold of the roundhouses and enter a space shared with the past. The interiors of the roundhouses are decorated with bright woollen cloaks and garments; shields hang from the walls. In the firelight of the central hearth eyes gradually adjust to the shadowy interiors to see beds, warp weighted looms and bread ovens and walls painted with curvilinear and anthropomorphic designs. In the bronze cauldron hanging over the fire the steam from a simmering stew mingles with the wisps of smoke curling up to the roof far above.

Over the years a great deal has been learned about the way the buildings decline and the need for constant maintenance to keep them viable as houses and safe for visitors to enter. The buildings change over time. As timbers rot in the ground adaptations are made accordingly. The outside appearance of a roundhouse may change with maintenance such as when roof caps are re-thatched as the thatcher tries a different style or a new design.

The Old Roundhouse

In the first full season under the ownership and management of the National Park in 1992, the Old Roundhouse was found to be virtually derelict and the interior was very poorly furnished. Hardly representative as the abode of the local elite! The roof was re thatched by 1993 and a wheat straw and sedge cap was constructed to protect the apex of the roof. This has been replaced three times in the last ten years and the roof area has been dressed and maintained every year. It was soon discovered that the more professional job undertaken also made it impossible for smoke to escape through the roof. If, as it has been suggested, chimneys were not a feature of Iron Age houses, and if roofs were thatched to a high standard, it would seem logical that charcoal would have been the most commonly used fuel. It is more efficient and produces less smoke; besides it would be very labour intensive to cut firewood into manageable lengths for the hearth using axes and small saws.

The posts set in the internal post ring and assumed to be supporting the roof had rotted in the ground by 1992 and were actually suspended from the ring beam. Although they were replaced it was clear that they had little or no structural value for the roof. Instead the ring beam was tied in place allowing the rafters to be placed alternately from wall to ring beam and from ring beam to apex considerably reducing the weight of the roof while also bracing it. Inner posts of this sort may have had a number of other purposes. For the Old Roundhouse we use the posts to form internal divisions and a storage loft although they could be interpreted as having a ritual purpose or even, if we cut them short, as supports for radial floor joists.

The interior has been furnished with simple beds of horizontal, split hazel hurdles and low frames of round timber packed with straw within wattle compartments marked by the inner post ring. A wattle-frame clay oven stands close to the central hearth over which an iron cauldron is suspended from the upper ring beam. An upright, warp-weighted loom is positioned by the door to gain the maximum light. Large looms like these would have been permanently placed within roundhouses, as they are too heavy and delicately set up to be moved in and out according to the weather (as often interpreted in illustrations of Iron Age settlements). A wide range of brightly coloured woollen blankets and rugs decorate the interior of the house. Wooden bowls and platters take the place of pottery in this aceramic part of Wales and baskets of all sizes contain fleeces, hides and other items to be expected within an Iron Age house.

The Smithy

This small roundhouse has an internal diameter of 6.5 metres. It has a simple construction of hazel wattle woven around stakes set about one metre apart. The rafters rest on a timber wall plate. As the height of the apex is only 3.5 metres, a ring beam was not considered necessary to support the roof. A cut drainage gully diverts ground water away from the walls and door area. The roundhouse is presented as a smithy because of metalworking evidence nearby. A fired clay bowl hearth and bellows form the focus of the roundhouse with tools based on published material from Danebury, Meare and Bulbury. Baskets and other goods together with the charcoal fire help to bring the roundhouse alive to visitors.

The Earthwatch

This roundhouse was constructed in 1989. A free-spanning roof was attempted without a ring beam. It was thought at the time that a ring beam would have to be supported by vertical posts as with the Old Roundhouse so one was not considered. Larch was used for the rafters, as oak was either not available or too expensive. The rafters rest on a jointed tension ring or wall plate and the apex was a confused jumble of rafter ends on construction.

The roof was thatched lightly with water reed allowing smoke to drift out but stopping the rain from so far entering. The apex was not capped allowing rainwater to rot the ends of the rafters. The north-facing door is very low utilising part of the tension ring as its lintel. As a result of this the interior of the roundhouse is very dark and not suitable for any precision craft activity such as weaving.

Over the years part of the roof has bowed increasingly with the force of the prevailing westerly wind due to the lack of a ring beam and the use of non-native softwood. To alleviate this, all the rafters have been propped with oak posts resting on stone slabs which do not compromise the archaeological evidence. The apex has been capped to protect the rafters. Of the large roundhouses the Earthwatch is the warmest and is often used for storytelling events.

The Granary

This four-post structure is approximately 2.9 by 3.3 metres in plan. The posts carry a floor that supports a circular, wattle and daub wall. A central post supports the rafters and the roof is thatched with water reed. The National Park completed the building in 1991.

As it has a floor raised off the ground this is the driest reconstructed building at Castell Henllys. The building has been used to store a range of goods including spelt wheat and celtic beans. These foods have been stored in tightly made baskets on the basis that sacks would have had to have been woven on a loom after the thread had been spun by hand on a drop spindle, a lot of hard work to produce such a humble item. Today the tenacity of the mice in gaining access to the store has been exceeded only by the energy of the grey squirrels that eat through the baskets to get at the grain. It is very difficult to keep the store fully secure; a challenge presumably shared with the original Iron Age occupants of the site and their own particular pests.

By 1993 the supporting posts, which had no packing, had already rotted significantly and had to be propped using large diameter timbers placed on the ground and wedged under the cross posts supporting the floor. In 2001 this is still the case and the structure is stable. The granary is capable of storing around forty baskets of spelt capable of containing around 1200 kilograms of grain. If the grain was stored loose or if sacks were in fact used the figure would increase greatly.

The Chieftain's Roundhouse

Perhaps Chieftain is too grand a term for the leaders of the local aristocracy probably based at Castell Henllys, but the roundhouse reconstructed most recently at the site ought to be suitable for one. The roundhouse was reconstructed over an Iron Age house platform with an internal diameter of thirteen metres and with no apparent internal structural features. The roundhouse was built around a temporary central king post. This facilitated the positioning of the rafters and the construction of a major wheel ring beam and smaller upper ring beam. Once the rafters and ring beams had been fixed in position, the king post was cut off just below the main wheel ring beam leaving a free-spanning roof.

The wall was constructed using hazel rods woven around wide diameter oak wall posts while the diameter below ground was much reduced by the removal of the bark and sapwood to extend its life. The wall was plastered with a daub mix containing clay, cow dung and straw and partially rotted water reed. Much care was taken in the construction of a jointed and pinned oak tension ring. The tension ring was designed to deal with the structural forces of the roof above ground in the knowledge that the posts below ground would rot out in little more than ten years. The construction techniques used were simple and many of the joints were also tied using hemp rope and twine but once the roof was thatched most of the rope became redundant as the weight of the thatch secured the joints.

The material requirement was very large including the equivalent of over thirty coppiced oak trees for the rafters, posts and ring beams and around ninety coppiced hazel bushes for the wattle walls. Two thousand bundles of water reed were used for the thatched roof and around two miles of hemp rope and twine.

Fittingly the roundhouse dominates the landscape around Castell Henllys. It is markedly visible from the A487 half a mile away. The original roundhouse occupying the house platform used for this project must have similarly dominated the landscape in the Iron Age.

The interior of the roundhouse has been carefully furnished and decorated to give the impression of wealth, comfort and status the occupants of a house like this would have enjoyed. Ash framed beds covered with fine, brightly coloured woollen blankets are separated by hazel and willow partitions; the walls are decorated with Iron Age designs in natural pigments. Oak benches have been carved with designs taken from decorated bronze votive plaques. A bronze cauldron hangs on chains above iron firedogs in the hearth. Decorated wooden bowls contain flour ground on nearby querns. The aim is to provide visitors with an indication of how comfortable and sophisticated life, for some at least, could be.

The material requirements for the construction of this large roundhouse would have had a considerable effect on the local landscape. It is clear that woodland management was widely practised in the Iron Age to enable the production of the large number of coppice products required for the construction of roundhouses and other structures. If water reed was widely used for thatching then reed beds too must have been carefully managed as valuable resources.

Around thirty thousand visitors experience Castell Henllys each year nearly a quarter of which are school children who visit to learn about the Iron Age in Wales as part of the National Curriculum for Wales. The reconstructed buildings are used to interpret Castell Henllys and the wider late prehistoric landscape of the National Park. Various activities and events take place each week to enhance the visitor experience in addition to the daily guided tours; these include Iron Age spinning and weaving demonstrations, storytelling, Iron Age craft activities and storytelling for children, living history demonstrations by site interpreters in period clothing and other craft activities.

Castell Henllys allows us to contemplate possibilities in the past and enable us to assess and test hypotheses over time. Most importantly they allow the public to engage with the past in a way usually beyond their reach.