Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(formerly loua), one of the most famous of the Hebrides. It is about three miles long, and varies in breadth from a mile to a mile and a half. In 1861 it had a population of 264. Its remarkable fertility was regarded as miraculous in the Dark Ages, and no doubt led to its early occupation. Dunii, the highest point on the island, is 330 feet above the sea-level. 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, as well from his kinsman Conall, the son of Comghall, king of the Scots, as from Bruidi, the son of Melchon, king of the Picts, 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 6th 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 (on Columba's account) Icolmikill, I-Columb-Kille, or Hii-Colum-Kille — that is, "the Island of Columbia of the Church." From the end of the 6th to the end of the 8th century Iona was scarcely second to any monastery in the British Isles; but the fierce and heathen Norsemen 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, abbot of the German monastery of Reichenau, in the Lake of Constance. 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 king Malcolm Canmore. It was visited in 1097 by king Magnus the Barefooted, of Norway, being at that time a part of that kingdom, and so fell under the ecclesiastical jurisdiction of the bishop of Man and the archbishop of Drontheim. In 1203 the bishops of the north of Ireland-disputed the authority of the Manx bishop, pulled down a monastery which he had begun to build in the island, and placed the abbey under the rule of an Irish abbot of Derry. The Scottish Church had long claimed jurisdiction in Iona, and before the end of the 13th century the island fell under the rule of the Scottish king. Its abbey was now peopled by Clugniac monks; and a nunnery of Austin canonesses was planted on its shores. Towards the end of the 15th century it 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 Cuildich, 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, believed to be the site of the monastery which the Irish bishops destroyed in 1203. St. Oran's Chapel, now the oldest church in the island, may probably be of the latter part of the 11th century. St. Mary's Nunnery is perhaps a century later. The Cathedral, or St. Mary's Church, seems to have been built chiefly in the early part of the 13th century. It has a choir, with a sacristy on the north side, and chapels on the south side; north and south transepts; a central tower about seventy- five feet high, and a nave. An inscription on one of the columns of the choir appears to denote that it was the work of an Irish ecclesiastic who died in 1202. 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; Godred, 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. — Chambers, Cyclop. 5, 619; Duke of Argyll, in Good Words, Sept. 1, 1869, p. 614 sq.; Princeton Rep. 1867, p. 1-22. (See Columba).
The Nuttall Encyclopedia 
A fertile little island 1½ m. W. of Mull, where St. Columba landed from Ireland A.D. 563, and built a monastery which was for centuries the centre of ecclesiastical life and missionary enterprise among the Scots of Scotland and Ireland and the Angles of the N. of England. It is 3½ m. long and 1½ broad.