Its presence in what was a house of enclosed monks is not explained, and it sits quietly above the filled arches without ceremony, alongside what may be a 15th-century mason's mark on a chamfered stone surround nearby. The tower itself, built of roughly coursed limestone rubble with cut sandstone arches, has had several lives: extended, partially blocked, vaulted, and at some point in the 16th century apparently converted into a fortified dwelling while the rest of the complex crumbled around it.

The monastery traces a long and complicated history. According to 19th-century antiquarian Samuel Lewis, the site was said to have been originally founded by St Patrick, with a monk named Guasacht appointed as its first abbot. It was formally refounded in 1205 by Lord Richard Tuit for the Cistercian order and dedicated to the Blessed Virgin. Tuit himself was interred here in 1211. The house was a daughter establishment of St Mary's Abbey in Dublin, and was also known under the Latin alias 'St Mary's de Lera alias de Grenardo'. By the early 15th century the buildings were in serious trouble. In 1410 the pope issued an indulgence, a formal grant of remission from punishment for sin, to those who gave alms toward the monastery's repair, with part of the complex already described as having collapsed. By 1422, a monk was writing to Rome to report that the monastery was 'threatened with ruin by the negligence of abbot Richard', suggesting the earlier fundraising had achieved little. A second indulgence followed in 1434 to 1435. After the dissolution of the monasteries under the Tudors, the site was leased to Richard Nugent in 1552 and later granted to Francis Shane in 1612.

What survives today is largely the three standing walls of the crossing-tower, the point where nave, chancel, and transepts once met, along with sections of the church walls and traces of the transepts. The original four pointed sandstone arches have been partially blocked, with smaller arches inserted into the fill. Beam holes, doorways, and putlog holes for scaffolding are still legible in the masonry. In the graveyard surrounding the ruins, scattered architectural fragments include a dumb-bell pier that once formed part of the cloister arcade. To the south, low earthworks under the grass mark out the footprint of the conventual range, and wide cultivation ridges visible in the field to the east may also be associated with the abbey's working life.