Past & Present

A Broch or a Dun?

Archaeologists are uncertain as to whether Dùn Bhuirgh is a broch or a dun, although it is perhaps a little small for a broch. Only excavation would clarify the matter. But whether it is a dun or a broch its function was the same – it was a prestigious statement of power built as a dwelling for a family of high status.

Without excavation, the classification of sites is a matter of comparison with other examples. Brochs are generally at least 15m in diameter. They were built as cavity-walled circular structures, some of which were three or more storeys high. Duns were solid walled buildings, often sub-circular in shape, of varied sizes, and never very tall. The collapsed walls of Dùn Bhuirgh now mask the features that would aid its classification.

broch recon.jpg
Broch Reconstruction by Alan Braby

Excavations elsewhere have revealed the standard form of a broch. From the 4m thick circular drystone wall at ground level two separate walls were constructed which narrowed as they rose in height. The wall at ground floor level was wide enough for the creation of small slab-roofed chambers. There is usually one on either side of the entrance passage, as well as one or two at other points around the broch wall.

Within the thickness of the wall a stone staircase was built that gave access to the upper level, with its wooden floor. In a few instances a further level was added, and so the tower was even greater in height. The cavity between the two walls at first floor level and above became increasingly narrow. Nevertheless, slabs were placed across it at regular heights almost to the tops of the walls. Here the timbers were set for a low conical thatched roof. However, there is no possibility that there was ever access and a walkway around the inside of the wall tops. While this was a feature of medieval castles, built with defence very much in mind, it was not an element in Iron Age brochs. Defence and security was a secondary consideration. Their primary function was as a permanent visual expression of power.

Archaeologists have shown that duns were architecturally distinct from brochs. They were constructed as solid, very thick-walled buildings usually with a much less regular shape than a broch. They were also much more varied in their ground-floor area, some being quite small, others very large. Like brochs, duns sometimes had chambers within the walls at ground floor level. However, they were never tower-like.

By Jill Harden

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