It is an unremarkable piece of urban ground, the kind easily walked past without a second thought. Yet this was once the precinct of a Dominican priory founded in 1237, a walled complex of church, tower, and outbuildings that hosted provincial chapters of the Dominican order four times between 1278 and 1314, suggesting a house of genuine standing within the mendicant world of medieval Ireland.

The priory's long decline is well documented. By 1432, a papal indulgence granted to fund repairs noted that a community of forty friars had once been maintained there, but that warfare and other unspecified calamities had reduced the resident community to barely eight priests, with both the church and the domestic buildings close to ruin. A survey conducted in 1540, shortly before the Dissolution of the Monasteries reached Westmeath, found the church roof thatched and collapsed, though the stone walls and windows were still described as being in sufficient repair. A stone tower and further buildings within the walled precinct were recorded as lately vacated and decaying. The site changed hands more than once after dissolution, passing to Sir Gerald Fitzgerald of Croyboy in 1548 and to Thomas Gorie in 1564. Then, in 1566, the crown granted the friary site to Walter Hope, a Dublin merchant, on the condition that he build a gaol there at his own expense, complete with stocks, locks, bolts, chains, and handlocks, and that he and his heirs reside in it as constable. The sacred and the penal thus occupied the same ground in Elizabethan Mullingar. Writing in 1682, Sir Henry Piers noted that the ruins of the priory were by then scarcely visible, with only part of the bell-tower and a few fragments still standing. By the late eighteenth century even those were reduced to crumbling walls in a garden at the edge of the town.

Two material traces of the priory survive elsewhere. A stone-lined well, possibly connected to the friary, lies in the backyard of the second shop on the south side of Dominick Street, the street name itself a corruption of the Dominican association. And the priory's seal matrix, a small metal stamp depicting the Holy Trinity and dating to the fifteenth or sixteenth century, is held in the National Museum of Ireland. A chalice presented to the Mullingar Dominican community in 1648, after the order had returned to the town in the seventeenth century, is kept at the Dominican Friary on Dorset Street in Dublin.