No surface trace remains of the early Christian monastery once founded here, and the ruins of the later medieval church that stood on the same ground had already been described as ruinous by the mid-seventeenth century. The site is known locally as Sean Ross Abbey, though it appears on the 1837 Ordnance Survey six-inch map under the name Corbally Abbey, and its layered past stretches from the seventh century to the aftermath of the Reformation.

The earliest chapter belongs to St Crónán, who according to an eleventh or twelfth century Latin Life of the saint came to this part of east Munster and built a church near Loch Cré, naming it Sean Ross. The place was then a wooded promontory extending into the lake, surrounded by poorly drained bogland, so secluded and inaccessible that Crónán eventually abandoned it in favour of a more convenient site at Roscrea, on the main road between Meath and Munster. He died in 665, and his feast day falls on the 28th of April. The monastery may also have carried the name Inshinamesh, a word that reflects its near-island character within the wetland. Centuries later, around 1140, an Augustinian priory was established at nearby Monaincha, roughly 1.7 kilometres to the east, and by around 1485 that community had relocated to Corbally. Following the dissolution of the monasteries, the Crown granted a lease on the site in 1566 to William O'Carroll and his son John. A 1568 inquisition noted that Corbally had been both a parochial and a monastic church, and by 1615 a Royal Visitation found the building still standing but locked against the Protestant minister and reserved for Catholic Mass. The Civil Survey of 1654 to 1656 recorded simply that upon the lands there stood "the ruines of an old church."

By 1840 a detailed description captured a cross-shaped structure measuring roughly thirteen and a half metres from east to west, with lateral arms extending north and south. The east gable carried a belfry buried in ivy, and the east window was built from chiselled brownish sandstone on the outside, with a double-pointed top and a central mullion that had already been removed. The round-headed doorway in the south wall was formed of finely cut sandstone blocks on the exterior. The south arm of the cross contained a large window in its gable, divided by perpendicular and horizontal mullions into four compartments, constructed of cut limestone. The 18th-century Corville House, built originally by the Prittie family, stood eighty metres to the west; in the nineteenth century it became the residence of John O'Byrne, created a Count of the Holy Roman Empire by the pope in recognition of his family's services to the church, and he was recorded as taking care to preserve the abbey building from damage. Nothing of that fabric is visible today.