By 1540, the church of an Augustinian priory in Naas was being used as a barn. That detail, preserved in a formal property extent drawn up around the time of the Dissolution of the Monasteries, says something quietly bleak about the fate of a religious house that had stood for roughly three and a half centuries. The priory dedicated to St John the Baptist has left almost no trace above ground in the modern town, yet the ground itself has been giving up fragments of it steadily, if slowly, ever since.

The Augustinian Priory of St John the Baptist was founded in the late twelfth century, though documentary references to it are scarce before the fourteenth. The 1540 extent paints an oddly vivid picture of what the precinct once contained: alongside the church-turned-barn there was a hall, a tower, stables, a dovecote, a watermill, and an orchard. That combination suggests a functioning, self-sufficient community at its height, even if the buildings had fallen into fairly inglorious reuse by the Tudor period. The priory site is believed to lie on or near the site of the present parochial house in Naas, and it was still referred to locally as St John's Abbey as recently as the nineteenth century. Excavations in the 1950s turned up sections of stone walling that may have been part of the complex. In 1990, archaeological testing uncovered a ditch roughly three and a half metres wide and over a metre deep, running approximately twenty-five metres north to south; two sherds of medieval Leinster Cooking Ware came out of it, and it was interpreted as a possible boundary ditch for the priory precinct. A font was also recorded at the site. Then, following testing in 1995, further work carried out in 2000 revealed something that had not previously been documented at all: a graveyard associated with the priory, lying quietly beneath the surface and unrecorded until that point.