It was built on a site which was then a marsh (hence “lake”) where, legend has it, a miraculous image of the Virgin which had escaped the Iconoclast destruction in Constantinople was found.
The icon, showing the Mother of God of Tenderness and previously in the Cathedral dedicated to Saint Catherine of Alexandria, is one of the relics of greatest importance in Bertinoro’s religious life. The new apse was built in 1702 and was decorated in 1714 by stucco artist Antonio Martinetti, with scenes showing the Eternal Father in Glory amongst the Angels and the Assumption of Mary into Heaven, and statues of Saint Anselm of Aosta, Saint Ildefonsus and Saint Peter Damian. They were the Fathers and Doctors of the Church who made the greatest contribution to the development of Marian theology. The façade was completed by Giulio Zambianchi in 1878.