Somewhere in the graveyard at Rathangan, a finely worked medieval stone sits repurposed as a humble gravemarker. It is a punch-dressed corbel, a projecting bracket once built into the fabric of an earlier church, and it now stands a few metres to the east of the north-east angle of the nineteenth-century Church of Ireland building. That single reused fragment is, in a sense, all that is physically visible of what was once the medieval parish church of Rathangan, dedicated to the Blessed Virgin Mary.

The documentary trail for that earlier church stretches back to 1297, when a Richard is recorded as vicar of the church of Rathangan. By 1302 to 1306, it was listed in an ecclesiastical taxation as a prebend of the diocese of Kildare, valued at 40 marks, with the vicarage rated separately at 30 shillings. A prebend was an income from church property assigned to support a cathedral clergyman, and the relative values here suggest a reasonably substantial parish. Over the following two centuries the prebend changed hands several times: in 1401 it was reserved for one Donald O'Connallam or O'Connolan by papal letter, and in 1427 a Richard Ó Hialáin received the same appointment. By 1580, Fr. Nicholas Eustace was serving at Rathangan as chaplain to the Countess of Kildare, and four years later the rector, one John Dalye, was charged with simony, the buying or selling of ecclesiastical offices or privileges. The medieval building did not survive intact into the modern period. By 1744 it had fallen into such disrepair that Robert, Earl of Kildare, left £200 in his will specifically for its rebuilding. The present Church of Ireland structure dates from the nineteenth century, and no memorial or monument predating 1700 is now visible within it.

The raised ground immediately to the east of the current church is subtly different from the rest of the graveyard, sitting noticeably higher than the surrounding area. That slight elevation may point to where the medieval building once stood, its foundations gradually subsumed beneath centuries of burial and soil accumulation. The corbel nearby, worn but recognisable, offers the most tangible connection to whatever church once occupied this ground.