The abbey was founded as a Benedictine institution in 978 by Willa, Margravine of Tuscany, in commemoration of her late husband Uberto, and was one of the chief buildings of medieval Florence. A hospital was founded in the abbey in 1071. The church bell marked the main divisions of the Florentine day. Between 1284 and 1310 the Romanesque church was rebuilt in Gothic style, but in 1307 part of the church was demolished to punish the monks for non-payment of taxes. The church underwent a Baroque transformation between 1627 and 1631. The prominent campanile, completed between 1310 and 1330, is Romanesque at its base and Gothic in its upper stages. Its construction was overseen by the famous chronicler Giovanni Villani.