Introduction
At the northern end of the broad summit of Knocknashee stand two large cairns, approximately 120 metres apart. Dating to the Neolithic period, probably within the fourth millennium BC, they form part of the remarkable passage-tomb tradition of County Sligo and are among the earliest surviving monuments on a hill that would remain a focus of human activity for thousands of years.
The two cairns are similar in overall size but differ considerably in appearance. The south-western cairn, SL032-013002, rises prominently above the plateau and contains a small exposed stone chamber. The north-eastern cairn, SL032-013003, is lower and more spread out, with no chamber visible today. Both are officially recorded by the National Monuments Service as passage tombs.
Figure 1. The two Neolithic cairns on Knocknashee, with the north-eastern cairn (SL032-013003) in the foreground and the south-western cairn (SL032-013002) beyond.
Their position is as significant as their surviving remains. From Knocknashee there are extensive views across the surrounding landscape towards other areas containing major prehistoric monuments, placing the cairns within the wider monumental landscape for which County Sligo is particularly important.
Thousands of years later, a substantial Late Bronze Age settlement developed across the summit around these much older monuments. The two cairns therefore provide not only evidence for the earliest monumental use of Knocknashee, but also a starting point for understanding the long and complex history of the hill.
The County Sligo Passage-Tomb Landscape
The two cairns on Knocknashee belong to a much wider tradition of Neolithic monument building in County Sligo. The county contains one of the greatest concentrations of passage tombs in Ireland, ranging from the large cemeteries at Carrowmore and Carrowkeel to individual cairns occupying prominent hills and ridges across the landscape. The Passage Tomb Landscape of County Sligo, currently included on Ireland’s UNESCO World Heritage Tentative List, encompasses approximately 95–100 passage tombs and undisturbed cairns.
The location of these monuments was an important part of their character. Passage tombs were frequently placed in prominent positions with extensive views, creating visual relationships between monuments, distinctive hills and other features of the landscape. The surviving cairns could themselves be visible over considerable distances, marking important places within a landscape used by Neolithic communities. This relationship between monuments and topography is particularly evident in County Sligo, where passage tombs occur from low-lying areas to prominent mountain summits.
Figure 2. View north from Knocknashee, with the north-eastern cairn in the foreground. Beyond lie the Ox Mountains, including Doomore with its passage tomb, while Knocknarea and its great summit cairn are visible on the distant horizon, with Benbulben beyond.
Knocknashee fits naturally within this wider setting. Its limestone plateau commands extensive views across South Sligo, while other important prehistoric landscapes can be seen from the summit. Knocknarea and Keshcorran are prominent on the wider horizon, while Knocknashee itself is visible from other monument-bearing uplands, including Keshcorran and Doomore. The two cairns therefore formed part of a landscape in which prominent hills and prehistoric monuments were often visually connected across considerable distances.
This wider setting is important when considering the Knocknashee cairns. Rather than viewing them simply as two isolated burial monuments, their elevated position and relationship with the surrounding landscape place them within a broader pattern of Neolithic monument building found throughout County Sligo.
The South-Western Cairn — SL032-013002
The more prominent of Knocknashee’s two Neolithic cairns stands towards the northern end of the plateau. It is a large circular, flat-topped monument measuring approximately 28 metres in diameter and surviving to a height of about 2.5 metres. Near its centre is a small roofed chamber, now exposed and accessible through an opening created by damage to one of its stones.
Figure 3. The south-western passage tomb (SL032-013002), showing the surviving cairn and the exposed chamber near its centre, with Muckelty Hill visible in the background.
The chamber measures approximately 1.7 metres north–south by 1.15 metres east–west and is about 1.1 metres high. Its construction is relatively simple, with single stones forming the sides and ends, a single slab forming the floor and a large slab forming the roof. Part of the northern end-stone has been broken away, creating the present entrance into the chamber.
The relationship between the chamber and the surrounding cairn is not fully understood. The Carrowkeel archaeological website compares the simple chamber with structures at Listoghil in Carrowmore and near Cairn K at Carrowkeel, suggesting that such chambers may originally have stood within smaller platforms before being incorporated into larger cairns during later phases of construction. Such a sequence has not, however, been archaeologically demonstrated at Knocknashee.
A number of scratched markings are also visible on the stones within the chamber. Some are clearly later graffiti, while markings on the western chamber slab have been compared with Early Christian examples elsewhere. Their date and significance remain uncertain, and they should not be confused with established examples of Neolithic passage-tomb art.
Figure 4. The south-western passage tomb (SL032-013002) on Knocknashee, viewed looking north. Photograph courtesy of Knocknashee Community Hub.
Despite disturbance over the centuries, the cairn remains a substantial monument, and the exposed chamber provides a rare glimpse of the stone-built structure concealed within it. Officially recorded by the National Monuments Service as a passage tomb, it forms one of the principal surviving monuments of Knocknashee’s Neolithic landscape.
The North-Eastern Cairn — SL032-013003
Approximately 120 metres north-east of the chambered cairn stands the second of Knocknashee’s two Neolithic cairns. Although almost identical in overall diameter, its surviving appearance is noticeably different. The monument consists of a broad circular cairn approximately 28 metres across and about 1 metre high, giving it a considerably lower profile than the south-western cairn.
Figure 5. The north-eastern passage tomb (SL032-013003) on Knocknashee, with the south-western cairn (SL032-013002) visible in the background.
Its most distinctive feature is a substantial concentration of stone towards the north-western edge of its flat summit. This forms a smaller cairn-like pile approximately 15 metres in diameter and 1.5 metres high, creating the uneven profile visible today. The present appearance may partly reflect later disturbance or modification of the cairn, although when this occurred and what form that activity took remain uncertain.
Unlike the south-western cairn, no chamber or other internal structure is exposed. Consequently, considerably less is known about its construction. What survives beneath the cairn material, and how closely its internal arrangement resembles that of its neighbour, cannot presently be determined without further archaeological investigation.
Figure 6. The north-eastern passage tomb (SL032-013003), looking north-west towards the Ox Mountains. Doomore, Knocknarea and its summit cairn, and Benbulben are visible through the mist in the distance.
The National Monuments Service records SL032-013003 as a passage tomb. Its position only 120 metres from the chambered cairn, together with its comparable overall size and prominent location on the plateau, places both monuments firmly within the Neolithic landscape of Knocknashee.
An Ancient Landscape Reused
The Neolithic cairns were not the final major phase of prehistoric activity on Knocknashee. More than two thousand years after their construction, the summit became the setting for an extensive Late Bronze Age settlement. More than fifty roundhouses have now been identified across the plateau, with excavations in 2017 dating the investigated houses to approximately 1230–850 BC.
The relationship between this later settlement and the much older cairns is particularly interesting. The roundhouses occupied the same summit while the two cairns remained prominent features at its northern end. By this time, the monuments had already stood for many generations, although there is no evidence to tell us what the Bronze Age inhabitants knew of their origins or what significance, if any, they attached to them.
The Late Bronze Age settlement, its roundhouses and the archaeological investigations undertaken between 2016 and 2021 are examined in greater detail in the link below.
Modern Archaeological Investigations at Knocknashee 2016-2021
Conclusion
The two Neolithic cairns are among the earliest surviving monuments on Knocknashee and form part of County Sligo’s wider passage-tomb landscape. Standing approximately 120 metres apart at the northern end of the plateau, they represent a phase of activity on the hill dating back more than five thousand years.
Much about the monuments remains unknown. Neither has been scientifically dated using modern archaeological methods, while the internal structure of the north-eastern cairn remains concealed. Nevertheless, both are officially recorded as passage tombs, and their scale and prominent setting are consistent with the wider Neolithic passage-tomb tradition of County Sligo.
Figure 7. Sunset over the Ox Mountains, viewed across the south-western passage tomb (SL032-013002) on Knocknashee.
Their survival also gives Knocknashee an exceptional depth of prehistoric history. By the time the Late Bronze Age settlement developed across the plateau, the cairns had already stood there for perhaps two thousand years. Today they remain the most prominent evidence of the earliest monumental activity known on the summit.
A Note on Visiting Knocknashee
The archaeological remains on Knocknashee have survived for thousands of years but are vulnerable to erosion and disturbance. Visitors are respectfully asked to avoid walking or climbing on the passage tomb cairns, and to avoid walking across the remains of the prehistoric roundhouses where possible.
Please enjoy the site with care and help ensure that these remarkable remains continue to survive.
Further reading
For further information on this subject, see the related material on the Achonry Mullinabreena Heritage & Culture website:
Sources and References
• Brandherm, D., McSparron, C., Kahlert, T. and Bonsall, J., 2018: “Topographical and Geophysical Survey at Knocknashee, Co. Sligo – Results from the 2016 Campaign”, Emania, 24, 81–96. Queen’s University Belfast
• Egan, Ursula, Byrne, Elizabeth, and Sleeman, Mary, with Ronan, Sheila, and Murphy, Connie, 2005: Archaeological Inventory of County Sligo, Volume I: South Sligo, Baronies of Corran, Coolavin, Leyny and Tirerrill, Dublin, Stationery Office.
• National Monuments Service, Historic Environment Viewer: SL032-013002-, Megalithic tomb – passage tomb, Knocknashee Common; SL032-013003-, Megalithic tomb – passage tomb, Knocknashee Common.
• Carrowkeel.com: “Knocknashee: The Hill of the Fairies.”
• World Heritage Ireland: The Passage Tomb Landscape of Sligo.
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