 The early dedication of the church to Mary is an assumption; the first documented mention of a church dedicated to Mary in Castelseprio (which is assumed to be this one) comes from the 13th century.The whole citadel was completely destroyed by Ottone Visconti, Archbishop of Milan, after he captured it in 1287, to prevent it being used again by his rivals.Investigations into the church, which began in 1934, finally uncovered the famous Byzantinesque frescoes below later plaster in 1944.