Excavations here revealed a rectangular palisaded enclosure, a fenced or staked boundary of the kind commonly used to demarcate sacred or significant ground in early medieval Ireland, measuring approximately eighteen metres from east to west. Within it, sixteen poorly preserved burials were found, twelve of them oriented in alignment with both the enclosure itself and a wooden shrine discovered in the eastern sector. The southern portion of the enclosure still runs underneath the later graveyard, which meant it could not be excavated at all, so the full extent of what lies there remains unknown.

The excavations were carried out on the island by de Paor during the 1970s, with findings published in 2013. Both the enclosure and the wooden shrine, a rare survival given how seldom timber structures leave any trace in the archaeological record, appeared to have been rebuilt on multiple occasions, suggesting sustained and deliberate use over a considerable period. De Paor concluded that they probably belong to a very early phase of the island's monastic history. Inis Cealtra, also known as Holy Island, is traditionally associated with Saint Caimin and carries a dense accumulation of early Christian remains, but this particular enclosure, predating or concurrent with the earliest formal structures above ground, points to a layer of ritual activity that the visible landscape gives little indication of.