Dún Aonghasa

Where it sits. Dún Aonghasa stands on the Atlantic edge of Inishmore, about eight kilometres west of Kilronan, on a limestone headland that ends in a vertical drop of roughly eighty-seven metres. The fort is a set of concentric drystone enclosures, three of them surviving where there were probably four, arranged in a half-circle whose open side is the cliff. Whether the missing half fell into the sea is one of the oldest arguments in Irish archaeology; the current view is that the site was always built against the edge rather than around a summit, which makes it a deliberately theatrical piece of architecture rather than a ruin.

The story behind it. Excavations by the Discovery Programme between 1992 and 1995, directed by Claire Cotter, established that people were living on the headland from about 1100 BC, in the Late Bronze Age, in huts inside the inner enclosure; bronze-working debris, clay moulds and food remains came out of the deposits. The great walls belong to a later phase, roughly 800 to 700 BC, and were reworked again in the early medieval period. Between the middle and outer enclosures lies a chevaux-de-frise: a broad belt of limestone slabs set upright in the ground, hundreds of them, angled to break the stride of anyone approaching at speed. It is the finest surviving example in Europe and it works — walking through it slowly is awkward enough. The name attaches the place to Aonghus, a figure from the legendary Fir Bolg, which is medieval storytelling rather than history. Much of what visitors see was rebuilt in the 1880s by the Board of Works, whose restorers raised wall heights and added terraces and steps with a confidence that would horrify a modern conservator, and the exact line between Bronze Age masonry and Victorian masonry is still debated.

On screen. The fort itself has rarely carried a scene, but it has framed a great many. Robert Flaherty's Man of Aran (1934) was shot in the townlands around it, and Gort na gCapall, immediately below the fort on the southern shore, was the home village of Flaherty's leading man. Nearly ninety years later Martin McDonagh's unit worked in exactly the same ground for The Banshees of Inisherin (2022): Dún Aonghasa is named among the Inishmore locations used, and the purpose-built cottage of Pádraic and Siobhán stood at Gort na gCapall, in the fields directly beneath the fort's walls. The silhouette on the ridge in wide shots of the island is this. Anyone walking up the approach path is following, more or less, the sightline that both films used to establish where they were.

What you actually see today. The visitor centre sits at Kilmurvey, at the foot of the hill, with a small exhibition and a café; from there a signposted track climbs about nine hundred metres over rising ground, stony and uneven in places, taking fifteen to twenty-five minutes. The path passes through the outer walls and the chevaux-de-frise before reaching the inner enclosure, which is about fifty metres across and contains a raised rectangular platform of natural rock at the very lip of the cliff, its purpose unknown and endlessly speculated on. There is no fence, no barrier and no edge marking of any kind. People lie flat and inch forward to look over; a standing figure in an Atlantic gust is taking a real risk, and the wind here regularly gusts hard enough to knock an adult sideways. Below, the swell works into the base of the cliff and the noise arrives a beat after the sight of it.

Getting there and timing. The site is managed by the Office of Public Works, with an admission charge and a seasonal timetable — longer hours from April to October, shorter in winter, and the last admission is well before closing to allow for the walk. Minibuses from Kilronan pier meet the ferries and drop at Kilmurvey; by bicycle the low road takes half an hour. The uphill path rules the site out for wheelchairs and makes it hard going with small children, though the beach at Kilmurvey below is sheltered, sandy and safe. Morning boats deliver a concentrated wave of day visitors between eleven and two; anyone staying overnight on the island can have the fort almost alone in the early evening, which is also when the low sun rakes across the terraces and shows the construction most clearly.