Nendrum: The Island Monastery and the Oldest Tide Mill

Nendrum, on Mahee Island in Strangford Lough, is the only major early monastic site in Northern Ireland whose excavation has been published in full. Tradition says St Mochaoi, who gave Mahee its name, founded it in the 5th century, and its abbots appear in the annals until 974, when the Four Masters record that the abbot Sedna Ua Demain was burned in his own house, perhaps in a Viking raid. Three dry-stone walls ring the hill, one inside the other, much of them rebuilt by H. C. Lawlor, who excavated the site between 1922 and 1924: the innermost holds a ruined church, the stump of a round tower and the graveyard, with a sundial of about the year 900 — one of the few early medieval sundials known — rebuilt from fragments found in the dig; the middle one held what the excavators called the monastic school, or workshop. On the shore below, a tide mill has been dated by its timbers to 619, the oldest excavated tide mill anywhere in the world. On the road out, Sketrick Castle guarded the causeway to the west of its own island.