In 1388, the "Consiglio Generale dei Seicento" prepared the construction of the church as a civic temple. To make room for the church, the adjacent Curia of Sancti Ambrosii was demolished, together with the majority of one of the city's burgs, including at least eight churches and towers. The first stone of construction was laid on 7 June 1390 under the supervision of architect Antonio di Vincenzo. Works lasted for several centuries: after the completion of the first version of the facade, in 1393 the first pair of side chapels were begun. The series were completed only in 1479.