It is so small that scholars have long debated whether it qualifies as a church at all in any conventional sense, and so old that Harold Leask, writing in 1955, considered it the oldest church in the county, a view echoed by the traveller Richard Pococke, who visited in 1752 and compared it favourably in antiquity with Ireland's round towers. Estimates of its date range from the 8th century to the 9th or 10th, and the uncertainty itself tells you something: this is a building that has simply outlasted the records that might explain it.

Dedicated to St Ultan, the church goes by several names depending on which century and which source you consult. Medieval documents refer to the parish variously as Kyltuly (1228), Glanmithithig (1410), and Gleande church (1418 and 1657). O'Donovan recorded the Irish name as Cill Ollta, while locally it was known as the Teampaill Fada, meaning the long church, which has a certain wry quality given its dimensions. No traditions or history concerning its foundation have survived, which is unusual even for early medieval Irish churches, where at least some hagiographical scraps tend to linger. Its single architectural flourish is a window in the east gable with a triangular head that splays inward and upward, a feature the antiquarian T. J. Westropp documented carefully in the early 1900s; the lower half of the window has since been blocked. The west wall, which an earlier visitor described as having a Gothic doorway, collapsed entirely during a storm in the mid-19th century and was rebuilt in plain, functional form. Until 1910 the ground around it served as a cillin, an informal burial ground for unbaptised children, though no trace of burials or markers now remains.

The site sits in Glen na Meade, and access is across rough grazing land, so footwear that can cope with uneven limestone and damp pasture is sensible. The church is a National Monument (No. 341), and nearby is Tobermurry holy well, worth seeking out on the same visit. Once inside the ruin, which you enter through the plain lintelled west door, look closely at the south wall: there is a small wall press, a shallow niche measuring roughly 42 centimetres wide, recessed into the stonework near the east end, and a single projecting stone on the exterior of the same wall whose purpose remains unexplained.