We are used to the word fort meaning defence against armies, but the cashel at Leacanabuaile was something more modest and more practical. The 9th and 10th centuries in this part of Kerry were a time of small landholders, cattle raids by neighbours, and occasional Viking trouble along the coast. The thick stone walls of a cashel kept livestock secure overnight, kept opportunists out, and signalled the householder's status. The site sits on a low rise with steep grassy slopes on three sides, so the only practical entrance is from the east, which is where the original gateway still lies. Inside is enough space, about thirty metres across, for a working family compound of huts, byres, and a hearth, plus the animals that meant survival.

Step through the eastern gateway and you find the interior arrangement that gives Leacanabuaile its character. There are three stone beehive houses, the corbelled drystone domes that western Ireland built for centuries because they suited the available stone and the available weather. The largest of them is intact enough to walk into. There is also a souterrain, an underground passage cut into the rock and lined with stone slabs, of the kind common in early medieval Ireland. Souterrains served two purposes, both useful: cold storage for dairy and meat, and a place of last resort if raiders came. They were narrow, low, and easy to defend from inside.

Excavated in 1939 and 1940, the cashel gave up the small objects of an ordinary working life. The list is plain and revealing: iron knives and pins, bone combs, fragments of bronze, a millstone, scraps of lead. Nothing aristocratic. Nothing that would make a museum's headline display. But every object speaks of the day-to-day labour of a household that lived here, ground its grain here, combed its hair here, and patched the bronze cookware that fed the family. The finds dated from the 9th and 10th centuries, the brief working life of the cashel before its occupants moved on or simply stopped maintaining the walls.

Leacanabuaile does not stand alone. Three kilometres northwest of Cahersiveen, and only a short walk from its slightly larger and more famous neighbour Cahergal, this is one of a small cluster of stone cashels that survive remarkably well in this corner of Kerry. The two forts together draw walkers up from the road through gentle pasture, and on a clear day the view from the parapet of Leacanabuaile takes in the inlet at Ballycarbery and the slate-coloured outline of Valentia Island beyond. The cows still graze around it. The hillside is still, in a small way, the milking-place that named it.