We know a great deal about the life of St.Columba. He went to Iona in 563. The settlement there would have been in the Celtic style., the monks living in seperate cells, coming together for meals and community prayer. From Iona the monks went to mainland Scotland, preaching the Gospel and setting up other foundations.
Columba went back to Ireland in 575AD where he defended the poets of Ireland at the council of Drumcaet. From there he travelled on, visiting some of his earlier foundations and founded the monastic settlement at Drumcliffe. He returned to Iona, which was now his home, and died there in 597.
Iona continued to grow and flourish, and during the 7th Century it had the largest library in Europe and there are supposed to have been 300 crosses. The Viking invasions meant the total destruction of the library and almost all the crosses - there are now only three left, the most famous being the cross dedicated to St.Martin of Tours. This cross was probabaly carved towards the end of the 8th Century.
Martin lived in France in the last years of the 4th Century. He was a soldier, a member of the Roman Imperial Army. He became a Christian but remained in the army to complete his appointed term. There is a famous painting by El Greco narrating a story from this period of his life - the sharing of his cloak with a beggar. At some time in his life he had read about St.Antony of Egypt who had left city life to live as a hermit in the desert. This appealed to Martin and when he left the army he set up a hermitage near Poitiers in France. He gathered other men around him on an organised basis. Each monk/hermit had his own cell but they all met for meals and communal prayers and were bound in obedience to the head of the settlement. When Martin was chosen Bishop of Tours he moved his fellow hermits to a settlement just over a mile from Tours and continued to live as a monk among them. It is a matter for conjecture how a cross on Iona in Scotland, an island that had such close and continuing connection with the Columban monasteries in Ireland, is dedicated to this French saint.