The church at Lurgoe, known in older sources under the name Derrynaflan, sits within an ecclesiastical enclosure and is surrounded, at varying distances, by medieval graveslabs, a burial mound, a ring-barrow, and a further enclosure to the west. A ring-barrow is a circular burial monument typically defined by a bank and ditch, and its presence here alongside early medieval masonry suggests this bogland island was considered significant long before the church was built. The whole site has the quality of somewhere that accumulated meaning gradually, layer upon layer, precisely because the dry ground was scarce and therefore worth holding.

The church itself is a multi-period structure, meaning it was built, altered, and extended across several centuries, and reading its walls is a way of reading that sequence. The earliest fabric is an early medieval nave constructed of cyclopean limestone masonry, a technique using very large, roughly dressed blocks, of which only the lower courses of the south wall now remain. In the 13th century a chancel was added to the east end, built in coursed limestone rubble and finished to a noticeably higher standard. Three single-light trefoil-headed windows survive in the chancel's south wall, and two more in the east gable; the trefoil form, a three-lobed arch, is characteristic of Gothic ecclesiastical work of that period. The sandstone jambs retain glazing-bar holes, evidence that these openings were once glazed. At the east end of the south wall there is a round-headed Romanesque piscina, a shallow stone basin used for rinsing liturgical vessels, decorated in sandstone. Still lying in the chancel interior is the triangular gable finial from the 13th-century roof, its socket still cut to receive a cross. There is also a small bullaun stone inside the church; bullauns are hollowed stones, often associated with early Christian sites, whose original purpose remains debated. Running northward from the nave's west end, a 13.1-metre length of wall with three rectangular external buttresses may represent the west range of a cloister, raising the possibility of a modest conventual complex here. Between 1676 and 1724 the site was associated with the Franciscans, though their own records do not indicate that a resident community was ever established. By the 17th century the church had already been recorded as ruinous and without services, and it had appeared in the Papal taxations of the Diocese of Cashel as far back as the 15th century.