That one of them is called the Church of the Dead, and that the enclosure wall holding them together contains two elaborately carved Romanesque doorjambs apparently salvaged from a demolished building and quietly reused as rubble, makes Inchcleraun something else entirely. The island sits in the stretch of Lough Ree that borders Counties Longford, Roscommon, and Westmeath, and its monastic complex is among the more densely layered early Christian sites in the Irish midlands.

According to legend, the island takes its name from Clothra, sister of the mythical Medbh, Queen of Connaught, though by the nineteenth century it was going by the altogether more prosaic name of Quaker's Island. The monastery itself was founded by St Diarmuid in the sixth century and adopted the rule of St Augustine during the twelfth century, by which point it had become a significant pilgrimage destination. The annals record at least two pilgrims who died there, Diarmuid O Braoin, coarb of Roscommon, in 1170, and Macbethaidh O'Dobhailen in 1193. The monastery was suppressed around 1541. Four of the churches sit within a large D-shaped cashel, a type of stone-walled monastic enclosure, roughly 180 metres north to south and 145 metres east to west, its straight side following the eastern shore of the island. A fifth church lies just outside the enclosure wall, and a sixth, known as Clogas, occupies the highest point of the island some 400 metres to the northwest. The southeast gap in the enclosure wall contains two carved Romanesque jambstones, the decorated uprights of what would have been an arched doorway. Discovered during maintenance works in 1932 and 1933, they were once proposed as evidence of a twelfth-century entrance gateway, but scholarly opinion has since shifted toward the view that they were lifted from a church doorway and inserted into the wall as reused material. Inside the enclosure, low grass-covered banks mark out a series of smaller subdivisions, and what the 1837 Ordnance Survey map labels a Vault in the northeastern interior is thought to be a post-1700 burial vault, now visible only as a slight rise in the turf. Of the six cross-slabs once located on the island, four have been removed to an OPW depot in Athenry, County Galway, and two are currently unlocated.

The island is accessible by boat from the Lough Ree shoreline, and the ruins sit in pasture on the eastern side. The carved jambstones in the southeastern wall gap are worth looking for closely; they are easy to pass without noticing, set into what appears at first glance to be a simple break in the drystone. A possible holy well dedicated to St Diarmuid lies about 180 metres to the southwest of the enclosure.