Achill Island Promontory Fort at Dun Bunnafahy

Achill Island Promontory Fort at Bun na Faiche (Dun Bunnafahy)

A quick overview of my coastal Discovery Series maps of the County Mayo coastline * reveals 54 marked promontory forts. Doubtless, this is fewer than there are actually are, as I doubt if they’ve all been recorded or transmitted to the mapping authority. One excellent example is the Achill Island promontory fort of Dun Bunnafahy (Dún Bun na Faiche, the fort at the bottom of the field), situated just south of the Wild Atlantic Way discovery point carpark at Ashleam Bay near Dooega.

Promontory Forts date from the Iron Age and are mostly found in Ireland, Cornwall, Orkney Islands, Isle of Man and Brittany. Not really ‘forts’, in the military sense, they are more likely to have been defensive structures, perhaps farmsteads, which made use of more or less narrow slivers of land jutting out into the sea. In that way, they were naturally protected on three sides by sea cliffs, meaning only one side needed to be reinforced with a defensive wall and ditch combination. MacAlister (1928) described them as ‘sites where a ditch and bank complex was constructed across the narrow isthmus of a natural headland’.

Dún Bun na Faiche

At this Achill Island promontory fort, the ditch and wall remain clearly evident, with the latter reaching a height of approx 6 metres from the bottom of the ditch. At the centre of the ditch, there appears to be a type of leveling off, as if a less deep entry passage.

View of defensive wall

Within the wall, immediately above this ‘bridge’, there are a number of standing stones still extant. Archaeologists consider these to mark the location of a cist. Indeed, it was suggested by Westropp (1914) that perhaps a child sacrifice may have been offered at the building of such a ‘fort’. I would have thought they’re more likely to be some kind of defended entry passage through the wall, not unlike what is seen at caiseals.

* Marked Promontory Forts of Mayo by OSI Discovery Sheets, excluding duplication (northeast to southwest) :

Sheet 24 – 1

Sheet 23 – 6

Sheet 22 – 30

Sheet 30 – 15

Sheet 31 – 0

Sheet 37 – 2

Total = 54

By the way, if you like this sort of thing, then you might also enjoy reading about Lios na Gaoithe ringfort. And here is a website that discusses Irish promontory forts in general.