In a major development for the archaeology of medieval Scotland, researchers have identified the remains of a previously unknown medieval castle at Loch Finlaggan on the Hebridean island of Islay.
Loch Finlaggan, located on the island of Islay off the western coast of Scotland, holds prominence as a significant archaeological landscape of medieval Britain. Finlaggan has long been recognised as the ceremonial and administrative centre of the Lordship of the Isles, and was traditionally viewed through the lens of its 14th–15th-century political apex, when MacDonald lords exercised quasi-independent authority across the Hebrides and parts of mainland Scotland.
The recent landmark scholarly publication, The Archaeology of Finlaggan, Islay: Excavations at the Centre of the Lordship of the Isles, 1989–1998, has offered the first integrated archaeological synthesis of three decades of fieldwork and analysis, fundamentally reframing the narrative of medieval power at Finlaggan. One of the most striking outcomes of this work has been the documentation of a previously unrecognised medieval castle, dating to the 12th and 13th centuries, long predating the classical Lordship complex.
Archaeological investigation at Finlaggan began in earnest in 1989 under the direction of David H. Caldwell on behalf of the National Museums of Scotland, in collaboration with the Finlaggan Trust. Excavations conducted through the 1990s on both Eilean Mòr (Great Island) and Eilean na Comhairle (Council Island) revealed extensive town-like complexes, including hall structures, domestic buildings, industrial zones, paved pathways and ceremonial spaces.
Previous investigations and research generally emphasised Finlaggan’s role during the height of the Lordship of the Isles (c 14th to 15th centuries) as a centre of governance, diplomacy, ceremony and law. Expanding on the earlier work, The Archaeology of Finlaggan, Islay provides an insight into earlier phases of the archaeology through detailed stratigraphic and architectural analysis.
Archaeologists have confirmed that the castle was a substantial complex spanning two small islands within the loch. On one, the foundations of a large rectangular stone tower were found. Given its scale, researchers believe it served as a keep or principal residence, comparable in ambition and style to contemporary strongholds found in England and Ireland at the time.
The tower was surrounded by an integrated hub on the neighbouring island on which the team identified all the elements needed for a functioning royal or elite administrative centre including courtyards, a great hall, kitchens and workshops, domestic quarters, and a chapel and burial grounds. These findings suggest that Finlaggan was an active seat of authority much earlier than previously thought. The quality of the stonework implies this was more than a simple defensive outpost—it was a statement of political power.
The main tower at Finlaggan is estimated to have measured roughly 19 × 19 metres at its base, comparable to large stone keeps elsewhere in Britain. Stone towers of this magnitude were typically associated with royal or elite households, particularly in contexts where visual prominence and defensive utility were both necessary. At Finlaggan the use of stone for construction may have served not only for defence but also for asserting the site’s importance for authority in the local and regional sense.
The Archaeology of Finlaggan, Islay outlines a sequence of the multiple phases of occupation across the centuries. The early castle phase, defined by the keep and courtyard complex, has been securely placed in the 12th and 13th centuries, based on stratigraphic relationships with overlying later constructions and associated artefacts.
The subsequent phase saw the development of a more palatial and administrative complex associated with the mature Lordship of the Isles, likely dating from the early 14th century onwards. In this phase, the architectural focus shifted away from a purely fortified tower to expansive halls, ceremonial spaces and administrative buildings, reflecting changes in the political needs and social practices of Finlaggan’s rulers.
Finlaggan’s early castle phase predates the period traditionally associated with the MacDonald Lords of the Isles (14th–15th centuries) and extends into a time when the political landscape of the western seaboard was highly contested. During the 12th and 13th centuries, overlapping influences from Gaelic rulers, Norse-Gaelic elites, and the expanding Scottish crown created a dynamic environment where coastal lordships could assert autonomy and develop complex political identities.
The construction of a large stone tower at Finlaggan suggests the presence or aspiration of a central authority capable of mobilising resources and labour at a high level. In many regions of Britain such fortifications were exclusive to powerful magnates or royal households; their presence at Finlaggan indicates a significant, albeit rarely documented, phase of political development in medieval western Scotland.
By the early decades of the 14th century, descendants of these earlier rulers (the Lords of the Isles) had consolidated their power across the Hebrides, Argyll and parts of the Highlands. At Finlaggan, this shift is evident in archaeological remains by the emergence of a structures oriented towards administration, ceremony and assembly. Written sources from the later medieval period refer to Finlaggan as the site of the Council of the Isles, where chiefs convened and where lords were inaugurated according to Gaelic custom.
The archaeological discoveries at Loch Finlaggan help enhance understanding of early political organisation in the western seaboard of Scotland. Far from being merely a ceremonial site of later centuries, Finlaggan was a focused centre of monumental authority as early as the 12th and 13th centuries, with a castle that rivalled contemporary strongholds in scale and symbolic power.
The Archaeology of Finlaggan, Islay makes clear that this early phase provided the foundation for the later Lordship of the Isles which went on to exercise broad regional influence and assert autonomy within the medieval British Isles. The castle at Finlaggan is thus a crucial archaeological testimony to shifting forms of medieval lordship, cultural exchange, and architectural ambition in the North Atlantic world.
Further reading:
- Caldwell, David (ed.). The Archaeology of Finlaggan, Islay: Excavations at the Centre of the Lordship of the Isles, 1989–1998. Society of Antiquaries of Scotland (2025). Open-access digital edition available online.
- Caldwell, D. H. (ed.). The Archaeology of Finlaggan, Islay. Society of Antiquaries of Scotland, Edinburgh.
- Caldwell, D. H. “Finlaggan and the Lordship of the Isles.” Proceedings of the Society of Antiquaries of Scotland.
- Oram, R. Domination and Lordship: Scotland 1070–1230.
- MacDonald, R. A. The Kingdom of the Isles: Scotland’s Western Seaboard.
- Woolf, A. From Pictland to Alba, 789–1070.