A church at the site, known as San Prospero di Castello, located inside the city walls, is known prior to 997. The church and its adjacent bell tower underwent reconstructions. In 1514, the church which was in ruins, was demolished and a new design by Luca Corti and Matteo Florentino was erected by 1527. Minor chapels were added till 1543, when the basilica was reconsecrated. Major changes to the belltower were designed by Cristoforo Ricci and Giulio Romano in 1536-1570. The facade of the church had been left incomplete till it was completed in 1748-1753 using designs of Giovanni Battista Cattani.