Around 700 AD three monks, sons of Nessan, a prince of the Royal House of Leinster, founded a monastery on Ireland's Eye. According to tradition it's here that the holy manuscript known as the Garland of Howth, now preserved in Trinity College, was created.
In the early 19th century, at the time of the Napoleonic Wars, a Martello Tower was built on the island to defend against attacks from France.
The island, now a Special Area of Conservation, has a rugged coast with a free standing rock formation known as 'The Stack'. Large numbers of guillemots, terns, gannets, razorbills, cormorants and puffins nest around the shore.