The Vikings destroyed all evidence of the original monastery at Iona, including most of the stone Celtic crosses, but in the early 1200s a Benedictine monastery and an Augustinian convent were built there. St. Benedict of Nursia (in Italy) is the author of the rule for life that continues to govern hundreds of monastic houses around the world 1500 years after his lifetime. During the so-called "Dark Ages" in Europe, after the collapse of the Roman Empire and destruction of much of its urban infrastructure by the tribes of the north, the monasteries and convents emerged as rural centers of learning.
The Roman Catholic Iona community continued to flourish until the Protestant Reformation. The Protestants, being a peaceable lot (akin to the Vikings) bent on reform, demolished most of the buildings and burned the library, and what was left gradually receded into oblivion. The abbey came under the control of the king and, eventually, private family ownership. A subsequent duke in that family line began some restoration work in the late 1800s, transferring ownership of the church properties to a foundation when he could no longer afford the work. The abbey was restored by the early 1900s and in 1938 the Reverend George MacLeod founded the contemporary Iona Community, which describes itself as "an ecumenical Christian community of men and women from different walks of life and different traditions in the Christian church that is committed to seeking new ways of living the gospel of Jesus Christ in today's world."
Today you can walk among the ruins of the convent cloister, visit the abbey buildings, and participate in the life of the Iona Community for a day, a week, a year, even up to three years. We will be living in one of the community residences and participating in its life -- liturgy, meal prep or cleanup, conversations with people from all over the world -- for a week.
Columba: The Celtic Dove ed. Kathie Walters
The Pattern of Our Days: Worship in the Celtic Tradition from the Iona Community by Kathy Galloway
Celtic Prayers from Iona by J. Philip Newell
Listening for the Heartbeat of God: A Celtic Spirituality by J. Philip Newell
The Isle of Iona by Alastair deWatteville
How the Irish Saved Civilization by Thomas Cahill -- and many thanks to Russell Smith! for this recommendation. All four Cahill books are in my summer reading pile, but I had not thought to check this one for Iona material.
You can see a panorama of the island's exteriors here (click and drag to move the panorama image in a circular motion), of the cloister here, and of the inside of the abbey here. The panoramas take a minute to load, but are well worth a look.
(Images from top to bottom: Celtic artwork on a cemetery monument here, the cover of the Book of Kells, the Abbey at Iona)