First, a baptistery annes is a building with a cathedral or a cathedral, where, in the past, was officiated the rite of baptism.
Why having a separate place from the the Cathedral?
This separation has its origins in the early centuries of cristianesimo when neophytes, still not baptized, could not enter the cathedral that was a consecrated place. So the baptism was held in the Baptistery.
The Baptistery of Florence is dedicated to St. John. Its construction dates back to XI-XIII centuries.
Its exterior is covered with white and green marble. Of particular importance are on the outside, the three bronze doors and all the mosaics inside the dome.
The three bronze doors are the South Gate of Andrea Pisano, with the life story of the Baptist and Allegories of the Virtues, the North Gate of Ghiberti, the Stories of the New Testament, Evangelists and Doctors of the Church. Finally, we have the East Gate (the most famous) also known as the Paradise: a masterpiece of Lorenzo Ghiberti was commissioned in 1425 and divided into ten panels that represent stories from the Old Testament.