The Gothic interior is vast and gives an empty impression. The relative bareness of the church corresponds with the austerity of religious life, as preached by Girolamo Savonarola.
Many decorations in the church have been lost in the course of time, or have been transferred to the Museum Opera del Duomo, such as the magnificent cantorial pulpits (the singing galleries for the choristers) of Luca della Robbia and Donatello.
As this cathedral was built with funds from the public, some important works of art in this church honour illustrious men and military leaders of Florence:
• Dante Before the City of Florence by Domenico di Michelino (1465). This painting is especially interesting because it shows us, apart from scenes of the Divine Comedy, a view on Florence in 1465, a Florence such as Dante himself could not have seen in his time.
• Funerary Monument to Sir John Hawkwood by Paolo Uccello (1436). This almost monochrome fresco, transferred to canvas in the 19th century, is painted in terra verde, a color closest to the patina of bronze.
• Equestrian statue of Niccolò da Tolentino by Andrea del Castagno (1456). This fresco, transferred on canvas in the 19th century, in the same style as the previous one, is painted in a color resembling marble. However, it is more richly decorated and gives more the impression of movement. Both frescoes portray the condottieri as heroic figures riding triumphantly. Both painters had problems when applying in painting the new rules of perspective to foreshortening: they used two unifying points, one for the horse and one for the pedestal, instead a single unifying point.
• Busts of Giotto (by Benedetto da Maiano), Brunelleschi (by Buggiano - 1447), Marsilio Ficino, and Antonio Squarcialupi(a most famous organist). These busts all date from the 15th and the 16th centuries.