The structure's present appearance is the result of numerous restoration campaigns that were carried out in different eras. The first radical interventions occurred after the fire of 1595, following which the roof was replaced and sculptors from the workshop of Giambologna, among whom were Gasparo Mola and Pietro Tacca, created the three bronze doors of the facade. In the early 18th century began the redecoration of the inside walls of the cathedral with large paintings, the "quadroni", depicting stories of the blesseds and saints of Pisa. These works were made by the principal artists of the era, and a group of citizens arranged for the special financing of the project. Successive interventions occurred in the 19th century and included both internal and external modifications; among the latter was the removal of the original facade statues (presently in the cathedral museum) and their replacement with copies.