A disused Church of Ireland building in County Kildare, complete with an octagonal spire and cusped Gothic windows, turns out to be layered over something considerably older. The nineteenth-century structure sits within the western sector of what appears to be an early ecclesiastical enclosure, and that enclosure itself lies within a possible medieval field system, giving the site a quietly compacted archaeology that the tidy Georgian Gothic exterior does little to advertise.

The church was built in 1829 to designs by John Semple (1801–82), a Dublin architect who worked extensively for the Board of First Fruits, the body that funded the construction and repair of Church of Ireland buildings in Ireland during the late eighteenth and early nineteenth centuries. Semple's handling of the Gothic Revival idiom at Feighcullen is recognisable from his other commissions of the same period: the same compact rectangular plan, the slender window openings, and the engaged west tower stepping up to an octagonal spire can be found at his Saint Tiernan's Church at Kilternan (1824–6) and Whitechurch Church (1825–7), both in County Dublin. At Feighcullen, the body of the building is rough-cut limestone, with dressed stone used for the quoins and window surrounds, and the chancel end is marked by a cusped east window, a detail that gestures at medieval ecclesiastical forms while remaining thoroughly of its own century. The site itself carries the additional weight of continuity: the parochial church stands on the location of an earlier church, meaning that whatever drew an early Christian community to this spot was reason enough, centuries later, for the same ground to be chosen again.