The church is particularly notable for its 44 stained glass windows, the largest undertaking of this kind in Italy in the 14th and 15th century. The windows in the aisles and in the transept depict saints from the Old and the New Testament, while the circular windows in the drum of the dome or above the entrance depict Christ and Mary. They are the work of the greatest Florentine artists of their times, such as Donatello, Lorenzo Ghiberti, Paolo Uccello and Andrea del Castagno.