Not Oxford, not Cambridge, but Llantwit Major (Llanilltud Fawr in Welsh) is probably Britain's oldest centre of learning. Scholars of church history have called it 'the Christian axis of the Celtic-speaking peoples' and 'the University of the Atlantic of the Celtic period', and the monastic community there was important across the whole of medieval western Europe. This book provides for the first time a history of St Illtud's monastery and school, founded in c.500 AD. It looks at developments on the site over the next 1,000 years till the Reformation, as well as at how the Celtic tradition and memory of Llanilltud have been kept alive since then. However, its primary focus is the development of the early monastic community in the context of the Celtic Christian tradition. A scholarly and analytical study, yet written in an engaging and highly readable style.