Both are repurposed fragments of the medieval church itself, one bearing carving from an elaborate multi-moulded doorway, the other from a traceried window, and they have ended up serving as grave-markers north and north-east of the ruin. Drainage chutes from the same building have been pressed into similar service. It is an quietly odd reversal: the ornamental elements of the church outlasting its structure by becoming furniture in the graveyard it served.

The site has a long and specific history. The place-name Grian appears in the Tripartite Life of Saint Patrick dating to around 450, and again in the Annals of the Four Masters for 914. The manor of Gren was granted to the Bishop of Emly in 1216, then to Maurice Fitzgerald, the justiciary of Ireland, in 1233, with a fair established the following year. By 1302 there was a recorded church and deanery at Grena. The medieval records that survive are fragmentary but vivid: in 1287, Agnes de Valence was forcibly deprived of the townland of Estgrene, valued at ten shillings, by Tatheg O'Brien, and later sought and received damages from Thomas de Clare. In 1318, the rector Galfrid Harold rescued a prisoner and was subsequently tried for the act. By the time the traveller Thomas Dineley sketched the church in 1680, part of it was already nearly levelled, though his drawing, now held as NLI MS 392, shows a chancel still in reasonable repair, along with a north door carrying a pointed arch, an ornate crocketed hood, and a stepped buttress. The Ordnance Survey of 1840 recorded that the roof had been removed in 1839 for planned repairs, but noted that a new church was likely to be built at Newpallas instead, leaving this one to be condemned.

What remains today is a sub-rectangular graveyard containing the footings and partial walls of a nave and chancel church, measuring roughly 17 metres east to west by 7 metres north to south internally, built from roughly coursed rubble limestone. The north wall has largely fallen, the east wall is grassed over to a height of about one metre, and the south wall is partially collapsed, though the west wall is in relatively better condition, reaching a maximum surviving height of around five metres at its tallest. A small rectangular addition at the west end has become an informal dumping ground for grave-clearance material and is now grassed over. The repurposed architectural stones used as grave-markers are the most informative objects on site, carrying evidence of decorative work that the standing walls no longer show.