It has been called Totmoy, Tuath muighe, and Castro Petre de Mortoto, and that accumulation of identities hints at just how many times this structure has been repurposed, altered, and partially erased over seven centuries. What survives is a limestone rubble church roughly 22 metres long, its walls still standing to a useful height but its interior considerably rearranged by nineteenth-century interventions, including three inserted family crypts that blocked up most of the original windows and destroyed the east window almost entirely. A single round-arched bellcote remains on the west gable where, according to the antiquarian Comerford writing in 1883, a double bellcote once stood.

The site began as a Franciscan friary, founded in 1325 after the minister provincial and the Friars Minor in Ireland accepted an invitation from de Bermingham to build a chapel and dwellings in his town of Totemoy, then in the diocese of Kildare. The Franciscans were a mendicant order, meaning they relied on alms rather than endowments, and their friaries tended toward long, relatively plain churches of the kind visible here. By 1550, a survey of Offaly described the friary walls as already 'burnyd and rasid', with two castles nearby, one newly built and one in ruin, alongside a mill and an orchard. At some point the building was converted for parish use, and in the sixteenth century it was granted to Nicholas Herbert, probably the occasion for a rebuilding phase evidenced by punch-dressed stone on the interior of the west wall. The church was abandoned in 1778. The earliest fabric still legible in the standing walls dates to the late thirteenth or early fourteenth century, visible in a narrow single-light window on the south wall whose jambs show diagonal stone tooling, a technique associated with the early medieval to transitional period. Intriguingly, a fragment of Dundry stone, a distinctive oolitic limestone quarried near Bristol and commonly imported to Ireland in the medieval period, was recovered from the graveyard, suggesting finer architectural ambitions at some point in the building's history. Scattered pieces of traceried window have also turned up among the graves.

The graveyard itself sits on flat ground with open views across the midland landscape, and it contains late seventeenth-century headstones worth examining closely. To the west of the enclosure, earthworks in the adjacent field may represent the deserted medieval settlement of Totemoy, and to the northeast lies a possible castle site that could be the original Castro Petre, or Peter's Castle. The whole cluster, church, graveyard, earthworks, and castle remains, amounts to an unusually legible trace of a medieval Anglo-Norman town that has otherwise entirely vanished.