Known as Cró-Inis or Cormorant Island, this site served as one of the royal seats of the Uí Máelsechlainn kings of Meath, alongside the nearby hillfort of Dun-na-Sgiath. The island’s strategic importance continued well into the medieval period when the O’Coffey clan built their tower house here, though their tenure would end in bloodshed. In 1446, according to the Annals of Connacht, Domnall O’Coffey and his two sons were murdered in their own home on the island by rivals from the O’Melaghlin and MacGeoghegan clans. The annalist notes, rather poignantly, that O’Coffey was “a man of wide accomplishment and his house was an open guest-house”, suggesting he was known for his hospitality before meeting his tragic end.

The ruins visible today reveal a compact square tower house, originally measuring about 4 metres internally, with thick walls that once rose considerably higher than their current height of just over a metre. When excavated in 1937 by R.A.S. Macalister, who curiously misidentified it as a pyramid, the building still retained features like a ground floor doorway on the north wall and a wall cupboard or aumbry; typical elements of a late medieval fortified residence. Stone pathways, roughly 2.3 metres wide, lead from the northern and eastern shores to the tower house, with the northern path connecting to what appears to be a medieval harbour or landing place cut into the shoreline. This small inlet, measuring about 5.6 metres long and 1 metre across, would have allowed boats to dock safely at the island fortress.

Archaeological evidence suggests the site’s history stretches back much further than the O’Coffey occupation. The crannóg itself, built of large stones and horizontal timbers contained within multiple palisades, dates to the early medieval period when it served the southern Uí Néill dynasty. Radiocarbon dating indicates it was re-fortified around 1107 AD, demonstrating its continued strategic importance over centuries. After the medieval period, the tower house appears to have been repurposed, possibly as a summer house or duck hide for the local gentry in the 1700s, adding yet another layer to this island’s long and varied history. Together with the nearby ringfort of Dun-na-Sgiath, Cró-Inis formed part of a royal settlement complex that controlled this crucial position on Lough Ennell for nearly a millennium.