Inside, the proportions are monumental. This grandiose, imposing architecture is certainly inspired by the Pantheon in Rome. The Baptistry is a real treasure chest.
The tomb of Baldassarre Costa, antipope with the name of John XXIII, is an extremely original work, probably done by Donatello and Michelozzo together. Then there are two noteworthy Roman-era sarcophagi, one of which is decorated with a scene depicting a boar hunt.
Originally, there was also the famous Mary Magdalene sculpted in wood by Donatello as well as the silver altar, absolute masterpiece of Tuscan goldsmith's art. Today, both works are preserved in the Museum of the Opera del Duomo.
The ornamentation of the walls, like the exterior, is completely given over to the two-color use of marble. The geometric motifs continue on the floor, inspired by Oriental and fantastic designs. The large, unadorned central octagon shows the location of the ancient baptismal font that was removed in 1567 for the baptism of Filippo de' Medici, Grand duke Francesco I's first-born son.
But the most difficult and costly job was probably the amazing mosaic decoration of the dome. It's a huge image divided into circles and slices that are read from the base of the dome up to the center. The work was started in 1270 and mosaic experts were brought in directly from Venice.
The image of Judgement Day is perhaps the most famous, and was done from a design by Coppo di Marcovaldo. Dominating over all is the great "Christ the Judge", at whose feet is the resurrection of the dead and the subdivision of souls.
But the figure that strikes the eye most is certainly the monstrous Lucifer, from whose ears spring terrifying animals: this is the Lucifer described by Dante in his Inferno, the demon with the three horrible faces that devours the damned, "the emperor of the kingdom of pain"
It's with the image of the Day of Judgement that ends the reading of the Baptistry's extraordinary figurative cycle: from birth to death and on to the afterlife, this masterpiece of art offers us an intense reflection on the sense of life - for all time.