That unglamorous etymology suits a site that has spent centuries being overshadowed, quite literally, by the city growing up beside it. What makes Mungret peculiar in Irish ecclesiastical terms is not its age or its ruins, but the story of an ambition that failed on a technicality: in 1152, at the Synod of Kells, the community here put forward a claim to be recognised as an episcopal seat, the seat of a bishop with formal diocesan authority. The claim rested on Mungret's long-established role as the principal church of the diocese of Limerick. The synod disagreed, and the reason given was essentially geographical: the monastery was simply too close to the town of Limerick, which had stronger arguments of its own.

The site's origins reach back to the sixth century, when the monastery was apparently founded by St Nessan. Its abbots are recorded from the middle of the eighth century, which gives a reasonable measure of its standing by that point. It was raided repeatedly between the tenth and twelfth centuries, a fate shared by most monasteries of any consequence in Munster during that turbulent period. After the Norman arrival in Ireland, the picture shifts considerably. At the close of the twelfth century, Domhnall Mór Ó Briain granted the land of Mungret to St Mary's in Limerick, and the site passed into the estates of the bishop of Limerick. By 1225 it had been granted the right to hold a weekly market, and by 1336 a rental document recorded in the Black Book of Limerick shows the local burgesses paying £4 10s. annually to the bishops for their land. A further entry in the statute rolls from 1463 to 1464 records that the borough had been granted the laws of Breteuil, a set of borough customs originating in Normandy that were widely adopted in medieval Ireland and England as a framework for urban governance. After that, the record goes quiet, and it is assumed the settlement declined during the famines and disruptions of the later medieval period.

The visible remains today are the cluster of church ruins on the south side of the Foynes road, and these are the most accessible part of a much larger, mostly buried, complex. Samuel Lewis, writing in 1837, noted that extensive building foundations had been found in the adjoining fields at considerable depth, turned up occasionally by the plough. That buried layer is not visible to a casual visitor, but it is worth knowing about when standing among the surviving stonework: what can be seen above ground is only a fragment of what once constituted one of the most significant Early Christian monasteries in north Munster. The site is reachable by road from Limerick city and the ruins are generally accessible on foot from the roadside.