Scheduled Monument

Thrumster House, broch 210m S ofSM13635

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
Prehistoric domestic and defensive: broch
Local Authority
ND 33198 45059
333198, 945059


The monument is a broch, a complex and substantial stone-built roundhouse dating from the Iron Age (between 600BC and AD 400). The broch is visible as a low, flat-topped circular wall with an entrance and intermural cell. The wall has been interrupted on its south side to accommodate a summerhouse built after 1871. The broch lies 70m above sea level in a relatively elevated position.

The monument was incorporated into the gardens of Thrumster House around 1790 and further landscaping was conducted around 1815. It is likely that early investigations were also conducted at around these times but little is known about them. Archaeological excavations were conducted in 2011 and this has enhanced our knowledge of the structure. The broch walls measure about 20.5m in external diameter and are about 4.5m thick. The top of the walls stand mostly about 1.2m above present ground level, but excavation shows the maximum wall height is at least 1.5m. Excavation has revealed part of a guard cell to the east of the southern interruption in the broch circuit, suggesting the original entrance was to the south; a secondary entrance lies on the west side of the broch. Excavation has also demonstrated that there is a gallery on the northwest side of the broch and an intramural cell to the north.

The scheduled area is circular on plan, measures 38m in diameter, and is centred on the centre of the broch to include the remains described above and an area around them 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 scheduling specifically excludes the above ground elements of the summer house.

Statement of National Importance

Cultural Significance

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

Intrinsic Characteristics

The monument is visible as a thick stone wall about 1.2m high. It is partially turf covered and mostly survives in good condition. The surrounding area is garden ground and part of the broch wall on the south side was removed to accommodate a summer house, probably in the late 19th century.

Historical sources suggest that during the construction and extension of Thrumster House a large quantity of stone was removed from the broch to provide building materials. Moreover, extensive groundworks were undertaken to tidy the broch and incorporate it into the landscape garden, probably around 1790 and 1815. The present, relatively uniform height of the broch is a product of this landscaping, and some of the masonry appears to have been rebuilt. Nevertheless, archaeological excavation conducted in 2011 demonstrates that much of the broch wall is of Iron Age date and contains features such an entrance on the western side, a gallery to the northwest, an internal cell to the north, and in situ occupation debris and artefacts including pottery and iron. The excavation also demonstrated that significant buried archaeological remains of Iron Age date survive in the vicinity of the broch, for example an earth bank between 2.5m and 4.5m east of the broch wall (AOC Archaeology Group 2012, 22 and Fig 6_3).  The excavations covered only part of the broch and its surroundings (AOC Archaeology Group 2012, Fig 1_1) and it is probable that further buried evidence exists within and around the broch that can tell us about how people lived, their trade and exchange contacts, and their social status, as well as providing information about broch architecture and construction methods. 

Radiocarbon dating of samples recovered from the broch suggests it may have been built in the 3rd or 4th centuries BC, with various phases of occupation and abandonment up to the 2nd to 4th centuries AD. It is already clear that it had a long and complex development sequence, during which the entrance was remodelled in a new location on the west and a new inner lining wall was constructed. Further scientific study of the site would allow us to develop a better understanding of the chronology of the monument, potentially clarifying its date of origin, state of completeness and development sequence.

Broch towers are 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 that may have changed over time.

Contextual Characteristics

Brochs are a widespread class of monument across northern Scotland with notable concentrations in Caithness, Sutherland, Orkney, Shetland, the Western Isles and the northwest Highlands. This example is of particular significance because of the remains of substantial and well-preserved walls. It was positioned on high ground that was later incorporated into a landscape garden; prior to this the monument is recorded as being located on a rocky crag. During the monument's use it would have been a prominent feature in the local landscape. Many broch towers were deliberately sited to be focal points in the landscape and this example occupies what would have been a dominant position.

The monument is located within 3 km of four scheduled brochs (scheduled monument references SM527, SM586, SM589 & SM883; Canmore IDs 9090, 8975, 8972, 8957). The proximity of these similar sites mean that this broch has the potential to enhance and broaden our understanding of prehistoric society and community in Caithness. There may have been links between these neighbouring brochs or they may indicate community catchments. There is high potential for comparative study on a local and national scale to better understand the function of such monuments, their interrelationship, the significance of their placing within the landscape and relationship to agriculture and economy, in particular in relation to our understanding of Iron Age social hierarchy, changing settlement patterns and systems of inheritance.

There are also numerous other prehistoric monuments in the landscape surrounding the monument, including a standing stone approximately 700 m to the southeast (scheduled monument reference SM541, Canmore ID 9020), and an extensive grouping of prehistoric cairns, stone rows and hut circles about 2.5km to the southwest on Battle Moss and within the vicinity of the Loch of Yarrows. There is potential to study these sites together to understand their functions within the local communities and possible chronological development in the area.

The monument is surrounded on its north, eastern and western sides by trees; the planting here mirrors the shape of the broch as part of the wider designed landscape around Thrumster House.

Associative Characteristics

Thrumster has some claim to the the first broch to be excavated in Caithness, and was among the first brochs to be excavated in Scotland (MacKie 2007, 448). A weaving comb was found at the site was presented to the National Museum in 1783, and excavations are known to have taken place around 1821. The broch is therefore associated with one of Scotland's earliest archaeological investigations.

Statement of National Importance

This monument is of national importance because it has an inherent potential to make a significant addition to our understanding of the past, in particular of Iron Age society in Caithness and the function, use and development of brochs. This example of a broch survives in an area with other broadly contemporary monuments; there is high 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. The visible broch wall and intermural structures within are impressive despite modern alterations and excavation has demonstrated the survival of buried remains including artefacts and ecofacts. The loss of the 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 the north of Scotland and further afield.




Historic Environment Scotland reference number Canmore ID 8963 (accessed on 11/07/2016).

The site is recorded as Thrumster Mains Broch (MHG2043) on The Highland Council's Historic Environment Record.

AOC Archaeology Group, 2012, Thrumster Broch Community Excavations: Final Report, AOC Project Number 60028, UK

MacKie, E. W. (2007) The Roundhouses, Brochs and Wheelhouses of Atlantic Scotland c. 700 BC - AD 500: architecture and material culture. Part 2 The Mainland and the Western Islands. BAR, vol 444. Oxford.

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. Page(s): 145, No. 502

HER/SMR Reference


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.

Scheduling is the process that identifies, designates and provides statutory protection for monuments and archaeological sites of national importance as set out in the Ancient Monuments and Archaeological Areas Act 1979.

We schedule sites and monuments that are found to be of national importance using the selection guidance published in Designation Policy and Selection Guidance (2019)

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).

The format of scheduled monument records has changed over time. Earlier records will usually be brief. Some information will not have been recorded and the map will not be to current standards. Even if what is described and what is mapped has changed, the monument is still scheduled.

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Printed: 26/05/2024 22:53