Iona, the most famous of the Hebrides, 1½ mile W. of the south-western extremity of Mull. Its modern name is believed to have originated in a mistaken reading of n for u; the word in the oldest manuscripts being clearly written Iona. From the 6th century to the 17th century the island was most generally called I, Ii, Ia, Io, Eo, Hy, Hi, Hii, Hie, Hu, Y, or Yi—that is, simply, 'the island;' or Icolmkill, I-Columb-Kille, or Hii-Colum-Kille—that is, 'the island of Columba of the church.' It is 3½ miles long, and 1½ mile broad. Its area, computed by Bede at 'five families' (or 'five hides of land,' as the passage is rendered in the Anglo-Saxon Chronicle), is 3½ sq. m., or 2264 acres, of which rather more than a fourth part is under tillage. The soil is naturally fruitful; its fertility was regarded as miraculous in the dark ages, and, no doubt, led to the early occupation of Iona. Dunii, the highest point of the island, is 327 feet above the sea-level. Pop. 247.
Its history begins in the year 563, when St Columba (q.v.), leaving the shores of Ireland, landed upon Iona with twelve disciples. Having obtained a grant of the island, he built upon it a monastery, which was long regarded as the mother-church of the Picts, and was venerated not only among the Scots of Britain and Ireland, but among the Angles of the north of England, who owed their conversion to the self-denying missionaries of Iona. From the end of the 6th to the end of the 8th century Iona was scarcely second to any monastery in the British Isles; and it was this brilliant era of its annals which rose in Johnson's mind when he described it as 'that illustrious island which was once the luminary of the Caledonian regions, whence savage clans and roving barbarians derived the benefits of knowledge and the blessings of religion.' But neither piety nor learning availed to save it from the ravages of the fierce and heathen Norsemen. They burned it in 795 and again in 802. Its 'family' (as the monks were called) of sixty-eight persons were martyred in 806. A second martyrdom, in 825, is the subject of a contemporary Latin poem by Walafridus Strabus. On the Christmas evening of 986 the island was again wasted by the Norsemen, who slew the abbot and fifteen of his monks. Towards the end of the next century the monastery was repaired by St Margaret, the queen of Malcolm Canmore. It was visited in 1097 by King Magnus Barefoot of Norway. It was now part of that kingdom, and so fell under the ecclesiastical jurisdiction of the Bishop of Man and the Archbishop of Trondhjem. In 1203 a Benedictine monastery was founded here, and a Benedictine (afterwards Augustinian) nunnery.
In 1506 Iona became the seat of the Scottish Bishop of the Isles, the abbey church being his cathedral, and the monks his chapter.
No building now remains on the island which can claim to have sheltered St Columba or his disciples. The most ancient ruins are the Laithrichean, or Foundations, in a little bay to the west of Port-a-Churraich; the Cobhan Cuilidh, or Culdees' Cell, in a hollow between Dunii and Dunbhuirg; the rath or hill-fort of Dunbhuirg; and the Gleann-an-Teampull, or Glen of the Church, in the middle of the island. St Oran's Chapel, now the oldest church in the island, may probably be of the later part of the 11th century. St Mary's Nunnery is perhaps a century later. The Cathedral, or St Mary's Church (c. 1203), whose ruin and precincts were made over by the late Duke of Argyll in September 1899, has a choir, with a north sacristy and south chapels; north and south transepts; a central tower, 70 feet high; and a nave. An inscription (defaced about 1849) on one of the columns of the choir seemed to denote that it was the work of an Irish ecclesiastic who died in 1203. On the north of the cathedral are the chapter-house and other remains of the conventual or monastic buildings. In the 'Reilig Oran'—so called, it is supposed, from St Oran, a kinsman of St Columba, the first who found a grave in it—were buried Ecgfrid, king of Northumbria, in 684; Godfred, king of the Isles, in 1188; and Haco Ospac, king of the Isles, in 1228. No monuments of these princes now remain. The oldest of the many tombstones on the island are two with Irish inscriptions, one of them, it is believed, being the monument of a bishop of Connor who died at Iona in 1174. To this interesting island a great Catholic pilgrimage took place in June 1888. For St Martin's Cross, see CROSS; see also the Duke of Argyll's Iona (1871; new ed. 1889), and other works cited at COLUMBA.