That acute angle is not ornamental; it is structural, a medieval solution to shedding water from a vault of mortared stone rather than timber and thatch. Alongside it, a small chamber known as the hermit's cell is reputed to be the burial place of the church's founder. A residential tower with stepped battlements projects above the roofline at the centre of the building, giving the whole ensemble an appearance somewhere between a parish church and a fortified residence, which is, in essence, exactly what it became over successive centuries.

The earliest part of the building dates from the mid-twelfth century, making the east end the oldest surviving portion. The saint for whom it was built, Doulagh or Duilech, appears in the ninth-century Martyrology of Oengus under the name 'Duilech of Clochar', which places his veneration well before the stone church itself was raised. The central tower was added in the fifteenth century, at which point the original west gable was demolished and the building extended; the stonework shifts noticeably between periods, with well-coursed masonry at the centre giving way to more irregular blocks at the east end. Fenestration spans the centuries too: a thirteenth-century double-light window with sandstone jambs sits at ground floor level on the east wall, while a trilobe cusped window lights the upper west chamber, and one window above it is made from tufa, a lightweight volcanic stone occasionally used in medieval Irish construction. Archaeological excavations in 1989 and 1990 recovered coins from the spring of the baptistry, the oldest being a posthumously minted silver penny of Henry VIII, along with pottery fragments dating from the thirteenth and fourteenth centuries onwards. Excavation of the chancel's north wall revealed a complete skeleton laid on a masonry plinth, with the skull placed inside a carefully cut recess in an upright stone, so that only the face remained visible before burial.