Scheduled Monument

An Dun, broch, ClachtollSM1831

Status: Designated


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The legal document available for download below constitutes the formal designation of the monument under the Ancient Monuments and Archaeological Areas Act 1979. The additional details provided on this page are provided for information purposes only and do not form part of the designation. Historic Environment Scotland accepts no liability for any loss or damages arising from reliance on any inaccuracies within this additional information.


Date Added
Last Date Amended
Prehistoric domestic and defensive: broch
Local Authority
NC 03670 27842
203670, 927842


The monument comprises a broch, a complex stone-built substantial roundhouse, dating from the Iron Age (between 600BC and 400AD). The monument is visible as a roughly circular drystone-walled structure with intramural galleries, guard cells and stairs. It is surrounded on the south, east and northeast by a mass of rubble, defined by the remains of a substantial stone wall. The wall is built of massive blocks and boulders, becoming a turf-covered stony bank to the north. The monument is located on a rocky knoll above the foreshore.

The broch occupies a sloping rocky knoll. It measures 16.8m in external diameter with a wall thickness averaging around 4m. Part of the western wall has been lost to coastal erosion. The entrance passage is on the northeast, over which there is a massive triangular lintel in the outer wall face. Door jambs and a bar-hole survive in the entrance passage which gives access to two guard cells. There are two further inter-mural galleries within the walls of the broch, one on the southeast side with a corbelled roof and another on the southwest and containing the stair and the stair foot cell. The stairs lead to the fragmentary remains of a first floor landing. The remnants of a further cell survives on the west side of the broch. There is a ledge around the interior of the structure. It averages 0.3m in width and is set at a height of 1.8m above the bedrock in the interior wall at the entrance passage. On the east side of the broch interior a curving drystone-lined passage is formed by the bedrock shelf enclosed by the broch wall.

The remains of a substantial wall extends around the landward side of the broch, extending to the cliff at each end. It stands almost 1m high in places. There is an entrance gap on the northeast and a curving path leading towards the broch entrance. Between the outer wall and broch is a mass of rubble, within which short stretches of walling are visible.

The scheduled area is irregular. It includes the remains described above and an area around within which evidence relating to the monument's construction, use and abandonment is expected to survive, as shown in red on the accompanying map.

Statement of National Importance

Cultural Significance

The cultural significance of the monument has been assessed as follows:

Intrinsic Characteristics

The monument is an example of a broch, visible as a drystone-walled structure set on a rocky knoll above the foreshore. Although part of the west wall has been lost to coastal erosion, the site survives in very good condition. The level of preservation of the broch together with the remains of outer-works are an important part of the monument's intrinsic characteristics and adds to its cultural significance.

Significant structural features survive within the broch, including guard cells, intermural galleries and stairs. The broch wall on the landward side stands to over 5m in height and there is evidence for significant reconstruction and remodelling of the structure in antiquity.

Excavation has revealed considerable detail about the broch, its construction, occupation and abandonment. The broch was destroyed by a catastrophic fire between 155 BC and AD 55 and does not appear to have been reused after this event. It was built on a sloping, rocky knoll of outcropping bedrock which the builders accommodated within the structure of the monument. The lower, landward side of the broch interior formed a curving passage that would have been located beneath floor level. There was a large central hearth that had been replaced at least twice and the floor of the broch had been covered with organic plant materials and clays. Considerable quantities of artefacts were recovered, including spindle whorls, pottery, steatite and sandstone lamps and bowls, a range of iron tools and a large assemblage of animal bones. The distribution of some of the artefacts suggests the presence of collapsed raised floors or platforms. A mortar or 'knocking stone' full of carbonised grain was recovered from the northeast quadrant of the broch. Further carbonised grain and organic materials were found in the southeastern inter-mural gallery.

The remains of outer-works in the form of a substantial stone wall and a mass of rubble survive on the eastern, landward, side of the broch. A curved path leads to the broch entrance and short stretches of walling within the rubble may indicate the presence of external structures. Although the broch itself has been excavated, the outer-works and any associated structures are likely to contain deposits rich in occupation debris, artefacts and palaeoenvironmental evidence that can tell us about how people lived, their trade and exchange contacts, and their social status. The broch and outer-works can tell us about the nature, construction and occupation of broch towers and the relationship between brochs, outer-works and external buildings.

Brochs are typically thought to date from the mid first millennium BC through to the early part of the first millennium AD. Outer-works and external buildings are general thought to have been built towards the end of the lifespan of brochs, likely during the 1st millennium AD. There are few precise scientific dates for brochs in northwest Scotland and their dating has traditionally been based on typological studies of artefacts recovered from broch sites. The presence of features such as the outer-works along with evidence of reworking of the broch structure itself indicates this site may have had a complex development sequence. Scientific study would allow us to develop a better understanding of the chronology of the site, its date of origin, state of completeness, survival of outworks, outbuildings or related structures, and any development sequence.

Broch towers are primarily seen as a specific specialised development of complex Atlantic roundhouses. They were large complex structures that could have accommodated either an extended family or a small community. While there would have been a social hierarchy within this community, the construction of these elaborate towers is often understood in terms of elite settlement. Other interpretations have stressed their likely role as fortified or defensive sites, possibly serving a community across a wider area. Brochs are complex structures likely to have had numerous purposes and a complex role in prehistoric society.

Contextual Characteristics

Brochs are a widespread class of monument found across northern Scotland with notable concentrations in Caithness, Sutherland, Orkney, Shetland, the Western Isles and the northwest Highlands. However, this example is one of only three brochs in Assynt. These brochs are located close to, or on, the coast. The other two examples are An Dun, broch 800m SSW of Ardvair (scheduled monument SM1832, Canmore ID 4550) 14km to the NE and An Dun, broch, 360m WSW of Kylestrome (scheduled monument SM1833, Canmore ID 4671) 19km to the northeast.

The monument is also significant for having outer-works and a relatively large enclosed area around the broch. Such features are more commonly found at some Orkney and Caithness brochs. There is therefore potential for comparative study on a local and national scale to better understand the function of such monuments, their interrelationship and the significance of their placing within the landscape. They have the potential to increase our understanding of Iron Age social hierarchy, changing settlement patterns and systems of inheritance.

The broch sits in a prominent position on a rocky knoll on the shore edge. There are wide open views in all directions. Many broch towers were deliberately sited to be focal points in the landscape, and this example would have been clearly visible from both the land and the sea. Its position on a sloping rocky outcrop added to the difficulties of building in such a location, but will have increased its prominence.

Associative Characteristics

There are no known associative characteristics which contribute to the site's cultural significance.

Statement of National Importance

The monument is of national importance because it has an inherent potential to make a significant addition to our understanding of the function, use and development of brochs in northwest Scotland. It is a well-preserved example of a broch that retains many architectural features and has significant outer-works. The broch can tell us about the construction, occupation and use of the monument. The outer-works have high potential for additional buried remains, including occupation debris, artefacts and ecofacts. The broch a prominent feature in the landscape and adds to our understanding of the siting of such monuments. This in turn can help our understanding of settlement patterns and social structure during the Iron Age in the Highlands. Brochs are relatively uncommon in Assynt compared to other areas of northern Scotland. The loss of this monument would significantly diminish our future ability to appreciate and understand the development, use and re-use of brochs, and the nature of Iron Age society, economy and social hierarchy in this area and further afield.



Historic Environment Scotland reference number CANMORE ID 4499 (accessed on 03/10/2018).

Highland HER Reference MHG13002 (accessed on 03/10/2018).

Clachtoll Broch project (accessed 03/10/2018)

Cavers, G. (2018) Clachtoll: saving an Iron Age broch. British Archaeology (March April 2018). pp 16-21.

Cavers, G., Barber, J. and Johnstone, N. (2018) Clachtoll Broch, Assynt: conservation and excavation. Data structure Report. AOC Archaeology Group, Unpublished report.

Close-Brooks, J. (1995) The Highlands, Exploring Scotland's Heritage series, 2nd. Edinburgh. pp. 145-146.

Feachem, R. (1963) A guide to prehistoric Scotland. 1st. London. p. 174.

Gifford, J. (1992) Highland and Islands, The buildings of Scotland series. London. p. 594.

MacKie, E W. (2007) The Roundhouses, Brochs and Wheelhouses of Atlantic Scotland c.700 BC-AD 500: architecture and material culture, the Northern and Southern Mainland and the Western Islands, BAR British series 444(II), 444(1), 2 V. Oxford. pp. 614-616.

RCAHMS (1911) The Royal Commission on the Ancient and Historical Monuments and Constructions of Scotland. Second report and inventory of monuments and constructions in the county of Sutherland. Edinburgh. pp. xix, xx, xxi, 2-3.

HER/SMR Reference

  • MHG13002

About Scheduled Monuments

Historic Environment Scotland is responsible for designating sites and places at the national level. These designations are Scheduled monuments, Listed buildings, Inventory of gardens and designed landscapes and Inventory of historic battlefields.

We make recommendations to the Scottish Government about historic marine protected areas, and the Scottish Ministers decide whether to designate.

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Scheduled monument records provide an indication of the national importance of the scheduled monument which has been identified by the description and map. The description and map (see ‘legal documents’ above) showing the scheduled area is the designation of the monument under the Ancient Monuments and Archaeological Areas Act 1979. The statement of national importance and additional information provided are supplementary and provided for general information purposes only. Historic Environment Scotland accepts no liability for any loss or damages arising from reliance on any inaccuracies within the statement of national importance or additional information. These records are not definitive historical or archaeological accounts or a complete description of the monument(s).

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An Dun, broch, Clachtoll, looking west-southwest, on a clear day with blue sky.
An Dun, broch, Clachtoll, looking north, with sea in the background.

Printed: 24/06/2024 01:26