What makes it quietly unusual is not just its age but its arrangement: the two churches on Kerry Head, one on the north side and one on the south, are said to have been founded by a brother and sister, each anchoring their own slope of the same headland, roughly two and a half miles apart.

The church is known in Irish as Teampall Daithleann, named for Daithlionn, a female saint reputed to be the sister of Erc, who is associated with the church on the southern side of Kerry Head. The building was a simple rectangular nave, constructed of large sandstone blocks, measuring 5.5 metres north to south externally, with walls nearly a metre thick. Its doorway, flat-lintelled and set into the south wall, is still visible, measuring roughly a metre wide and 1.8 metres high. By 1841, when the Ordnance Survey documented it, the west gable had already gone, though a window in the east gable was still partially intact; the surveyor John O'Donovan recorded it as built of chiselled brown stone, with a round arch on the inside and each stone running the full thickness of the wall. That window has since disappeared. Folklore collected from Booleenshare School noted that the walls had collapsed before 1814, and added a detail the stonework cannot supply: that Daithlionn had lived in a small cabin beside the church, spending her life in prayer there, and that people once travelled to see both the church and the saint's little house. Immediately to the east of the ruin lies Tobar na Súl, the Well of the Eyes, a holy well whose waters were traditionally visited on Saturdays by those suffering from ailments of the eyes, and which the 1841 Ordnance Survey recorded as dedicated to Daithlionn herself. The valley, the glen, and the saint's name have remained bound together in the Irish place name, Gleann Daithleann, ever since.