As you enter the building, your attention is immediately drawn by the precious mosaics in the dome, one of the largest domes in the world in its day to be decorated using this technique. The mosaics are dominated by the huge figure of Christ in Judgement, with scenes from the Last Judgement occupying three of the dome's eight segments. The horizontal registers superimposed in layers tell the stories of St. John the Baptist, the patron saint of Florence, of Jesus, of Joseph and of the Creation of the World. The Angelic Hosts occupy the highest register of all, in the centre of the dome.
Under the patronage of the wealthy Arte di Calimala, the Guild of Merchants, Finishers and Dyers of Foreign Cloth, the baptistry was also given its three sets of splendid bronze doors.
The oldest set is the South Door, cast by sculptor Andrea Pisano between 1330 and 1336. Its twenty uppermost panels depict episodes from the life of St. John the Baptist while the remaining eight portray the Christian Virtues.
The North Door, the second to be made and basically modelled on the first, contains scenes from the New Testament in its twenty uppermost panels and the four Evangelists and four Church Fathers in the other eight.
And finally, the East Door, which Michelangelo called the Gates of Paradise, is the now fully Renaissance masterpiece of Ghiberti and his assistants, who included Luca della Robbia. Ghiberti and his workshop won the commission for the door without a competition, changing the design to ten large panels instead of the twenty-eight smaller ones on the earlier doors.
The baptistry originally housed several other major works of art, including Donatello's Penitent Magdalene and a Silver Altar, both now on display in the Opera Museum for conservation purposes.