Description

The monument comprises a broch dating to the Iron Age (800BC – 400AD). It survives as a roughly circular mound of rubble approximately 18m in diameter with associated earthworks. It is located on a low knoll to the east of the River Naver at approximately 11m above sea level.

The broch was a circular drystone structure measuring approximately 9m across internally within a wall 4m thick. The remains of the entrance passage and drystone chamber had been previously observed in the north side of the wall. On its south side there is a possible internal doorway which would have accessed a chamber or stair within the thickness of the broch wall. The earthwork defences take the form of a curved inner ditch measuring 35 long and 7m wide and an outer rampart measuring 40m long and 5m wide and extends to the north and west. A subrectangular building orientated north-northwest to south-southeast and up to 10m long has been insterted on the east side of the broch and to the southwest is a circular stone enclosure approximately 7m wide. Both are of unknown date. 

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. The above ground elements of all current post and wire fencing are specifically excluded to allow for their maintenance. 

Source: Historic Environment Scotland

Statement of Scheduling

The national importance of the monument is demonstrated in the following way(s) (see Designations Policy and Selection Guidance, Annex 1, para 17):

a.  The monument is of national importance because it makes a significant contribution to our understanding or appreciation of the past, as a broch with the potential for multiple phases of occupation dating to the Iron Age (800BC – 400AD). 

b.   The monument retains structural, architectural and other physical attributes which make a significant contribution to our understanding or appreciation of the past. This includes the visible earthwork defences, and beneath the collapsed rubble, the potential for traces of the entrance passage, drystone chambers, hearths and stairs along with evidence relating to the construction, use and abandonment of the broch.

e.   The monument has research potential which could significantly contribute to our understanding or appreciation of the past. Archaeological excavation is likely to identify well stratified archaeological deposits with a good potential for surviving artefacts and environmental remains suitable for scientific analysis and radiocarbon dating. 

f.   The monument makes a significant contribution to our understanding of the historic landscape. It is located an area of fertile agricultural land with views along Strathnaver. A comparative study of the broch with similar monuments on a local and national scale could help us to better understand the reasons behind their distribution, changing settlement patterns and land use.

 Assessment of Cultural Significance

This statement of national importance has been informed by the following assessment of cultural significance:

Intrinsic characteristics (how the remains of a site or place contribute to our knowledge of the past)

The monument comprises a broch dating to the Iron Age (800BC – 400AD). 

Brochs are large round drystone towers with an internal wattle and timber structures and the potential for associated external buildings, structures and earthwork defences. The monument was first described in the map notes of Timothy Pont's map of Strathnaver (Pont 2) dating to the late 16th century. The notes state  'at achailly Borgenn - is a Denns (Danes) brugh' perhaps suggesting it was a more prominent structure than now survives. 

Within the walls of the broch the remains of an entrance passage, chamber and internal doorway have been previously identified. The doorway is likely to have provided access to a further chamber or a stairway to an upper floor. In the post medieval period stone from the broch was robbed out in order to construct the nearby settlements (Canmore ID 6221).   

Building such structures would have taken a significant amount of time and resources and there is the potential for multiple phases of occupation, repair and reuse over an extended period of time. Excavations at An Dun, broch, Clachtoll in Highland (scheduled monument SM1831) has shown that the interior space was used for variety of domestic activities. A wide range of artefacts were recovered there from undisturbed archaeological deposits sealed at the time of the broch's destruction by fire. These including bone and antler needles and combs; a fragment of a wooden bowl; stone querns and knocking stone filled with charred cereal grains; spindle whorls and lamps; iron agricultural tools; copper alloy pins and sherds of pottery.  Environmental remains were also present and from these radiocarbon dates have dated the occupation of the broch to the Middle Iron Age, specifically 176 BC to AD 65 (Cavers 2022).

Achcoillenaborgie broch has not been excavated. Beneath the remaining collapsed material the internal structure, including hearths, intermural stairs and cells is likely to survive. This is an important factor to the monument's significance.  

The broch and its associated enclosing ditch is also likely to contain stratified archaeological deposits from which samples can be gathered for environmental analysis and radiocarbon dating. A broad range of artefacts can also be expected to survive and these have the potential to tell us about the social status and lifestyle of the inhabitants, including dress, diet, metal working; the local economy, as well as trade, contact and conflict. Detailed study of the broch can tell us how the monument developed over time, in particular, its occupation and construction, use, reuse, repair and abandonment along with its relationship to its outer defences.

Contextual characteristics (how a site or place relates to its surroundings and/or to our existing knowledge of the past)

The monument is located on a low knoll within an area of fertile low-lying ground. The River Naver lies approximately 85m to the west and 100m to the east the ground rises sharply to steep crags. Approximately 327m to the north is the  Allt Ach Coille na Borgie Burn. The broch would have had extensive views of the surrounding landscape and would have been well defended by the ramparts on the gentler approaches. 

Brochs are found only in Scotland. They are a widespread class of monument with notable concentrations in Caithness, Sutherland, Orkney, Shetland, the Western 

Isles and the northwest Highlands. Brochs occur less frequently in central and southern Scotland. There are at least 12 known brochs in the Strathnaver area, 9 within the strath itself and 3 along the shores of Loch Naver. Those closest to Achcoillenaborgie broch are Lochan Druim an Duin, broch 320m E of (scheduled monument SM1879; 2.3km to the northwest) and Allt a'Chaisteil, broch E of Rhinovie, Strathnaver (scheduled monument SM1828; 2.2km south-southeast). Swanson notes that the brochs appear to be associated with surrounding cultivable land (1988, 237). Occupants of the broch may have controlled access to or farmed these areas themselves. 

The Strathnaver is rich in settlement and cultivation remains dating from the Bronze Age (2,500 BC – 800 BC) to Iron Age (800 BC – AD 400). Examples close to the broch include Achcoillenaborgie – cairn field and hut circles (Canmore ID 6272; 290m west-southwest); Achnabourin hut circle (Canmore ID 6210;743m southwest). Cairnfields in close proximity to hut circles are characteristic of prehistoric agriculture. These remains can also be found in close proximity to ritual  monuments such as Achcoillenaborgie, cairns 500m N of Lochan Duinte (scheduled monument SM1781; 400m south-southeast) and Invernaver, cairns, cists, hut circles & field system 1000m NW of (scheduled monument SM2842; 2.1km northwest).

The broch can be studied in relation to the wider agricultural and settlement pattern within in the strath and across Scotland to help us better understand prehistoric land use over time and identify regional trends and differences. There is also potential for the monument be included in a larger study to better understand the connection between brochs and earlier ritual sites. The broch would have been a significant component in the prehistoric landscape and is likely to have had a role in its organisation. The remains of the broch are still a prominent feature which contributes to the character of Strathnaver.

Associative characteristics (how a site or place relates to people, events, and/or historic and social movements)

There are no known associative characteristics which contribute to the monuments cultural significance.

Source: Historic Environment Scotland

Sources

Bibliography

Historic Environment Scotland http://www.canmore.org.uk reference number CANMORE ID 6221 (accessed on 09/05/2023).

Local Authority HER/SMR Reference MHG10772 (accessed on 09/05/2023).

Clachtoll, An Iron Age Broch Settlement in Assynt, North-West Scotland. Oxbow. Oxford.

Cavers, G. (2022) Clachtoll. an iron age broch settlement in Assynt, north-west Scotland. Oxford: Oxbow Books.

Pont, T (ca. 1583-96) Strathnaver; Kyle of Tongue - Pont 2(1). Available at https://maps.nls.uk/view/00002283 (accessed on 22/06/2023).

Swanson, C.B. (1998) A Contribution to a New Understanding of Brochs. Volume 1. Ph.D. Thesis, Edinburgh University. Edinburgh Research Archive. Available at http://hdl.handle.net/1842/19332 (accessed on 12/05/2023).

Lock G and Ralston I 2017. Atlas of Hillforts of Britain and Ireland. [ONLINE] Available at https://hillforts.arch.ox.ac.uk. (accessed on 12/05/2023).

Canmore

https://canmore.org.uk/site/6221/

Source: Historic Environment Scotland