The complex roundhouses of the Scottish Iron Age: An architectural analysis of complex Atlantic roundhouses (brochs and galleried duns), with reference to wheelhouses and timber roundhouses

This study investigates the architectural complexities of the roundhouses of the Scottish Iron Age. Scotland’s geographical position in northwest Europe has led to it being labelled as archaeologically peripheral to mainstream Iron Age developments. The mundane nature of the material culture contrasts, however, with the elaboration of the buildings, the roundhouses. Although timber roundhouses are typical of Britain’s later prehistory, it is the evidence of drystone buildings in the north and west that is unique to Scotland, the complex Atlantic roundhouses (cARs) and wheelhouses. Based on field inspections, survey drawings by the Royal Commission on the Ancient and Historic Monuments of Scotland (RCAHMS) and surprisingly few modern excavation reports, cARs are selected as a case study to identify objectives in spatial arrangements and structural design. The findings are compiled in a catalogue and visualised in reconstructions that do not propose standard solutions, but explore alternatives, primarily for building parts that do not survive: upper floors and roofs. Analogies for these reconstructions are derived from the record of post-medieval architecture of rural Scotland that shows a similar regionality to cARs regarding material and construction. Since architectural analysis has rarely been applied to prehistoric architecture, the present study may provide an example for approaching comparable buildings that predate written history.

The results suggest that cARs were architecturally highly developed buildings, a product of experience and experiment, with no evidence for strict standardisation. Their design was guided by shared principles, but also produced regional and even individual variation. This variation was adjusted to the local conditions of environment and materials. Deformation and collapse indicate an experimental approach to construction, and perhaps the limits of structural understanding of the Iron Age builders. The design objectives for cARs are confirmed by comparison with other contemporary roundhouse evidence, namely wheelhouses and substantial timber roundhouses. Overall similarities in layout and structural systems show close links that override the differences between these house types in material and construction. A picture emerges of awareness, if not direct contact between the different Iron Age communities across Scotland. The differences in the individual house design highlight that such shared principles were flexible to accommodate strong regional traditions and apparently individual requirements. Supraregional relations, regional identity and personal circumstances could all be expressed through the medium of the roundhouse.