Scheduled Monument

St Mary's Abbey, Iona, monastic settlementSM12968

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
Supplementary Information Updated
Crosses and carved stones: cross (free-standing), Ecclesiastical: abbey; enclosure; monastic settlement
Local Authority
Argyll And Bute
Kilfinichen And Kilvickeon
NM 28747 24526
128747, 724526


The monument comprises the remains of the large early historic monastic settlement founded by St Columba in AD 563, St Martin's Cross, and parts of medieval buildings associated with the Benedictine Abbey of St Mary founded around AD 1200. Parts of the bank and ditch that surrounded the monastic settlement are visible as upstanding features, particularly on the west side of the monument. Elsewhere, archaeological excavations and geophysical surveys demonstrate that complex archaeological remains of the monastic settlement survive below ground. The foundations of the medieval abbey buildings underlie the church, cloister and associated structures reconstructed during the 20th century. St Martin's Cross stands to the west of the present abbey church. The monument lies on the east coast of Iona, around 500m north of the pier at St Ronan's Bay. It stands at around 20m above sea level on ground that slopes down eastwards to the sea. The monument was last scheduled in 1971, but the documentation does not meet modern standards: the present rescheduling rectifies this.

The site of the medieval abbey lies close to the centre of a complex series of banks and ditches, some visible as upstanding earthworks, others buried below the present ground level. These features form at least three concentric enclosures, approximately square or rectangular in shape but with rounded corners. Overall, the enclosures cover an area measuring about 360m NNE-SSW by 280m transversely, approximately 10 ha in extent. On the north side, a very slight spread bank with an external ditch represents the outer enclosure, lying about 150m beyond the abbey buildings. Geophysical survey indicates that other boundary features, probably inner enclosures, lie buried 60m north and 90m north of the abbey buildings. To the west, the north end of the outer enclosure survives as a large and impressive earth rampart with an external ditch and counterscarp bank, at least 110m long and with a combined width of 15m. Here, the rampart is several metres high (measured from the base of the ditch). Further south, the west side is less visible, but a gap on Cnoc nan Carnan, 150m west of the abbey buildings, may represent an entrance. North of this gap, the rampart is at least 2m high (measured from the base of the ditch). To the south, it divides, with one bank turning to the south-east, and a second continuing south then turning gradually to the east. Geophysical survey suggests the position of an inner enclosure at the north end of the west side, immediately east of the modern road. South of the abbey buildings, no earthwork banks or ditches survive to the east of the road, but geophysical survey indicates a complex arrangement of enclosure features, including features that appear to continue the lines of both of the main earthworks visible west of the road. Excavation north-east of St Oran's Chapel has verified that a substantial ditch exists on the line of the inner enclosure suggested by geophysics. A natural slope about 75m east of the abbey buildings may represent the outer enclosure on the east side. Geophysical survey indicates buried boundary features 20m and 40m east of the abbey buildings, corresponding with the two inner enclosures also identified on the north side. Beyond the enclosures, a raised causeway known as Iomaire Tochair crosses the low ground to the west and is oriented directly towards the abbey buildings. Limited archaeological investigations of the enclosures suggest that one of the outer banks on the west side may have been built before the arrival of Columba, whereas the inner enclosure ditches on the south side may have been open in the 6th to 7th centuries AD.

There are no upstanding early historic buildings within the enclosures, but a very large and artistically important collection of carved stones provides evidence for the early historic monastery. Amongst the most important stones are a fine high cross from about AD 800, known as St Martin's Cross, that stands 21m west of the abbey church, and St John's Cross. A replica of St John's Cross stands west of the abbey, while the original (now restored) stands in the reconstructed infirmary building. The earliest visible building is a small stone structure standing close to the west end of the later abbey church. Known as St Columba's Shrine, it was once a free-standing chapel, built probably in the 9th or 10th centuries. The chapel was rebuilt in 1962, but its original walls stand to a height of 1m. With this exception, all of the stone structures visible today date to a time after control of Iona had passed to the Lords of the Isles. After St Columba's Shrine, the earliest standing structure is St Oran's Chapel, built around the mid 12th century, possibly by Somerled. It stands 80m south-west of the present abbey buildings in Reilig Odhrain, the graveyard probably used by early Scottish kings. The chapel is a simple structure resembling contemporary Irish churches and may have been built as a family burial chapel. It was re-roofed and restored in 1957.

The Benedictine abbey was built around 1200 and was developed in six further phases of building ending in the 15th century. Most of the present abbey buildings represent a combination of medieval masonry from the 13th to 15th centuries and modern masonry from the 20th-century restorations. The exception is the west range, built in the 20th century as a new structure. The abbey church is cruciform. When built around 1200, it consisted of an aisle-less nave and choir with two transepts. There is evidence for an undercroft introduced beneath an aisled choir in the 13th century, and then removed in the 15th century, when there was a major rebuilding campaign that saw the removal of the nave aisles, widening of the nave and crossing, and construction of the south transept, west front and east end. The church was restored between 1900 and 1910, but there is extensive survival of 13th- to 15th-century masonry both above and below ground level. To the north, buildings are laid out around a cloister and represent the former chapter house and dormitory in the east range and the refectory, above an undercroft, in the north range. A further range to the north represents the abbot's house and reredorter. Again, these cloistral buildings show extensive survival of 13th- to 15th-century masonry, both above and below ground level. Two detached structures lie to the north-east: the former infirmary, which stood only 0.5m high before restoration in 1964; and the Michael Chapel, built around 1200 and intact to wallhead height in 1875, when it was restored. A fine collection of medieval sculptured stones, including several West Highland grave slabs, is contemporary with the medieval buildings. Many of the grave slabs lay in the cemetery of Reilig Odhrain, but are now housed in the cloister and infirmary.

In addition to the visible remains, the many small archaeological excavations carried out since the 1870s demonstrate very high potential for important buried structures and deposits to exist over wide areas of the site. Wall foundations exist below the church and beyond the south transept; the eastern edge of a probable 7th- or 8th- century post-built structure probably survives north-east of Reilig Odhrain; more post-holes may occur west of the west range; and deep archaeological deposits lie east of the east range.

The area to be scheduled is irregular on plan, to include the remains described above and an area around them within which evidence relating to the monument's construction, use and abandonment may survive, as shown in red on the accompanying map. The scheduling specifically excludes the above-ground elements of all buildings except St Oran's Chapel. This means that the above-ground elements of the abbey church, the cloistral buildings, the abbot's house, reredorter, infirmary and Michael Chapel are among the structures excluded. The sculptured stones housed within excluded buildings and the replica of St John's Cross are excluded from the scheduling. The scheduling specifically excludes the metalled surfaces of all modern roads, paths, yards and car parks, and the above-ground elements of all fences, gates, modern walls, street furniture, street lights, flood lights, signs, information boards, wooden pedestrian bridges, benches, telegraph poles, railings, posts, chains, flag poles, washing lines and bins to allow for their maintenance. The scheduling specifically excludes the above-ground elements of the sculpture in the abbey cloister and the sculpture east of the MacLeod Centre. The scheduling specifically excludes all water tanks and sceptic tanks, together with the soil vertically above them, and the buried heat pump room to the east of the abbey. The scheduling specifically excludes all active burial lairs and the above-ground elements of all burial monuments of 19th-century or later date.

This scheduling was amended in 2015 to clarify that the above-ground remains of St Mary's Chapel and Tigh-an-Easbuig are not excluded from the scheduling and form part of the scheduled monument.

Statement of National Importance

Cultural Significance

The monument's cultural significance can be expressed as follows:

Intrinsic characteristics

Although there have been many archaeological investigations since 1870, archaeologists have excavated only a relatively small proportion of the monument as a whole. The excavations have not provided a clear plan of the Columban monastery, but they have established beyond doubt that the site contains very significant buried remains with very high potential to provide information about the layout of monastic centres from the 6th to 16th centuries and the types of activities their inhabitants conducted.

The monastic settlement lies within a complex group of enclosures. Radiocarbon dating of the peaty topsoil found beneath the bank to the west of the site gave a date in the 1st or 2nd century AD. This highlights the possibility that there was an existing enclosure here surrounded by a bank and ditch before the arrival of Columba and his companions. The complexity of the earthworks and geophysical anomalies suggests that the boundary features date from more than one period and were developed over time. Excavation north-east of St Oran's Chapel corroborates this, suggesting two successive ditches perhaps filled in during the 6th and 7th centuries. Excavation of the boundary features has been minimal and they offer great potential to understand how the extent and layout of the monastery evolved.

A church must have existed at the core of the monastery, a sacred space that was central to the life of the community. Communal buildings for the monks to sleep and eat in probably stood nearby. Researchers suggest that these structures would originally have been built of wood, with the church not replaced by a stone structure until the 8th century of later. The location of the Columban church is not yet known. Although it has been argued that it stood in the vicinity of St Oran's Chapel, a position nearer the centre of the enclosures, close to or beneath the later Benedictine abbey, seems more likely. Again, there is great potential for buried remains to enhance our understanding of the early monastic buildings. Excavation shows that the area around the Benedictine abbey was not completely cleared during the restoration works. Buried post-holes suggesting the position of two or three relatively early timber buildings have been recorded about 10m west of the west range, and there is potential for similar features to exist nearby. The survival of the small chapel known as St Columba's Shrine suggests that there were stone churches within the monastery by at least the 9th or 10th centuries. There is high potential for the buried foundations of other early stone churches to survive and excavation has demonstrated the presence of mortared foundations south of, and pre-dating, the abbey church. Buried remains have high potential to augment our knowledge of the early history and development of this monastery's church, as well as early medieval church architecture in general. There is additional potential for early graves to exist, in association with the church or in one or more monastic burial grounds. Documentary sources suggest that Scottish kings were buried at Iona from around AD 850. Reilig Odhrain is the potential location for these burials and it is likely that early graves may exist here. Burials have the potential to provide information on the population over an extended time period, though people who lived their lives away from the island may also be represented. Burials can enhance our knowledge of status and burial practice, but can also reveal evidence for health, diet, illness, cause of death, and perhaps the types of activities people undertook during life.

Excavations and historical sources both suggest an extensive craft zone must have existed to service the monastery. Some of the finest early historic metalwork and illuminated manuscripts were produced on the island, the manuscripts probably including the Book of Kells. Archaeological investigations have revealed buried evidence of metal- and glass-working at several locations, including the infirmary building north-east of the abbey complex and an area close to Reilig Odhrain to the south-west. Sherds of imported pottery from France and north Africa have been found, for example from a 'working area' north-west of the abbey buildings. There is potential for buried deposits to contain further evidence for the trade and exchange networks that linked Iona with other parts of Europe. The excavations near St Oran's Chapel demonstrate that the preservation of organic archaeological remains in backfilled enclosure ditches is excellent, and that artefacts of leather and wood, as well as animal bones, all survive. Organic remains can inform our knowledge of the character of the local landscape and the agricultural and craft activities that were practised. It is clear that the remainder of the site has exceptional potential to provide further information about many aspects of an early monastic community. We can expect evidence for crafts such as vellum, metal and glass production, that would add to our knowledge of manufacture and use of different artefact types and the artistic styles used. Building foundations from a range of structures may provide evidence about the construction and architecture of many different buildings within the monastic sites.

There is potential to trace the use of the site and the development of monasticism over an exceptionally long period of time. It is probable that archaeological deposits exist that will enable a better understanding of the period during and after the Viking raids, improving understanding of the relationship between Christian Iona and the pagan Scandinavians. Firstly, this may include evidence for violent raids, perhaps in the form of destruction layers and burnt horizons, or even human remains preserving pathological evidence for violence. Secondly, there may be evidence for longer-term Scandinavian involvement with the monastery, perhaps settlement or portable artefacts that might suggest a developing social or economic relationship between Scandinavians and the monastery. Subsequently, buried remains offer the opportunity to improve our understanding of the development of the Benedictine abbey and the lives of the monks and agricultural workers who lived there, and the patrons and pilgrims who visited.

Contextual characteristics

Early historic monastic settlements known to have surviving physical remains are rare in Scotland. Nevertheless, archaeologists have excavated large areas within the monastic enclosures at Whithorn, Hoddom and Portmahomack, as well as remains at Inchmarnock and on the Isle of May. These sites allow researchers to set the findings from Iona in context, enhancing their significance.

Iona has particular significance as the monastic settlement established by Columba and his followers when they came from Ireland. It was easily reached from Ireland by sea and originally probably reflected Irish models of monastic layout and architecture. We can compare it with early churches sites at Glendalough, Innishmurray, Clonmacnoise, Moville and Armagh. However, Iona also spawned a group of monasteries in northern Britain and itself acted as an influence on monastic settlements founded over a wide area. Most notably, Aidan travelled from Iona to Northumbria to found Lindisfarne, while Portmahomack may have been founded by Columban missionaries travelling from Iona to Pictland. More locally, we can be confident that Iona had a very direct impact as Christianity spread up and down the west coast of Scotland. Although relatively remote in today's landscape, its coastal location resembles that of many other monastic sites at a time when the sea would have been the main communication route allowing movement around a network of monastic communities.

Iona, through the remains already excavated and those known to be preserved beneath the ground, adds to our understanding of the infancy of Christian communities in Scotland, revealing national similarities and regional diversification. It offers the potential to examine the connections between ecclesiastical sites and the ways that Christian culture was dispersed. In particular, it has great potential to enhance our understanding of Christian missions. The workshops may prove to be places where monks produced items such as books and chalices, equipment necessary for setting up new Christian communities and disseminating new ideas and practices.

Contact with Ireland continued for many centuries, but the Viking raids also saw the start of a period of Scandinavian influence, which continued after the foundation of the Benedictine abbey. Iona then lay within the diocese of Trondheim and parts of the abbey reflect Scandinavian architectural taste. However, the founding of a Benedictine house also brought Iona closer to mainland Scotland, and the layout and form of the abbey can be compared with Benedictine houses on the mainland such as Dunfermline Abbey and Coldingham Priory.

Associative characteristics

Iona is mentioned by early authors who describe the crucial role it played in the conversion to Christianity of the peoples of Scotland and northern England. St Columba's arrival at Iona in AD 563, his founding of a monastery and its long-lasting influence are described in two important texts: the 'Life of St Columba', written before 704 by Adomnan, ninth abbot of Iona; and the 'Historia Eccesiastica' written in 731 by the Northumbrian monk, Bede. Adomnan describes a mission by Columba to the northern Picts about the year AD 565, suggesting that Columba met the Pictish ruler Bridei near Inverness and founded monasteries that survived at least to Adomnan's time. Many aspects of this story appear mythical rather than historical, but it indicates a perception that Iona played an important part in Christian contact with the Picts. Bede refers to the Northumbrian king Oswald's exile among the Scots and to his subsequent request for them to send a bishop to develop Christianity in Northumbria. Aidan was sent from Iona and established a new monastery at Lindisfarne. Bede comments that Iona 'was for a long time the principal monastery of nearly all the northern Scots and all the Picts and exercised a widespread authority'.

Although the documentary sources leave no doubt about the importance of Iona, the accounts we have are partial and problematic and do not provide simple descriptions of the site. Adomnan gives glimpses of the life of the monastery, referring to fishing nets and deer traps, salt stores, harvest labour, book satchels, hand bells and ink horns. But his main concern is to demonstrate that this was a place full of divine favour and he uses idealised motifs to make his point. Any detailed understanding of the monastery's layout, buildings and economy will be dependent on the potential of the buried archaeological remains.

Monasteries were centres of power, wealth and industry and, as such, were prime targets for Viking raiders. There is potential to discover archaeological evidence for Viking attacks, which would allow comparison with historical accounts and illuminate a well-known episode in popular history. Our knowledge of Iona in the centuries after the Viking raids is shadowy, but it remained of sufficient importance for a succession of Scottish kings to be buried there between 850 and 1100, including Kenneth MacAlpin who is credited with uniting the Scottish and Pictish kingdoms.

The remains of the Benedictine monastery have an uncertain relationship with Columba's earlier community, but are important structures in their own right. They represent the continuing sanctity of the island in the medieval period, illustrating the shifting character of social and religious life in Scotland. After the Reformation, interest in the ruined buildings grew in the late 17th and 18th centuries and it is questionable whether many antiquarian visitors realised that the ruins they saw were not those of Columba's community. From the 18th century, the abbey buildings have been a well-known symbol of the medieval Christian world. The site continues to be of international cultural significance attracting both tourists and modern day pilgrims from around the world.

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 to early historic monastic settlements and the spread of Christianity across the British Isles. With its often complex and well-preserved archaeology, this site has the potential to make a very significant contribution to our knowledge of monastic layout, economy, and art. Archaeologists have so far investigated a relatively small part of the site overall and there is very high potential for other future discoveries. Deposits deriving from continued use of the enclosure after contact with the Vikings may provide evidence to illuminate a poorly understood period of Scottish history and augment the sequence known from Whithorn. The abbey buildings have been a poignant symbol of the medieval Christian world since the 18th century. The loss of the monument would significantly diminish our future ability to appreciate and understand early historic monasteries and the central role of these power centres in the conversion of Scotland to Christianity. The abbey is known as 'the birthplace of Scottish Christianity' and remains a place of international cultural significance, not just for pilgrims and tourists but for the whole of Scotland.



RCAHMS records the Early Christian monastery as NM22SE 4.00 and the abbey as NM22SE 5.00. The WoSAS SMR records parts of the monastery as WoSAS Pins 244, 245, 246 and the abbey as WoSAS pin 258.


Adomnán, Adomnán of Iona. Life of St Columba, ed R Sharpe, London: Penguin, 1995.

Bede, Ecclesiastical History of the English People, ed B Colgrave and RAB Mynors, Oxford: Clarendon Press, 1969.

Carver, M 2008, Portmahomack Monastery of the Picts, Edinburgh University Press.

Historic Scotland Properties in Care, undat Statement of Cultural Significance ' Iona Abbey buildings

O'Sullivan, J, 1998 'More than the sum of the parts. Iona: archaeological investigations 1875-1996', in Church Archaeology 2, 5-18.

Historic Environment Scotland Properties

Iona Abbey

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Related Designations

  1. IONA ABBEYLB12310

    Designation Type
    Listed Building (A)

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