Battistero di San Giovanni is probably the ancient churches in Florence. It is octagonal in shape and totally covered in white and green marble. Considered as quite possibly the most delightful places to visit in Florence, the Battistero di San Giovanni is important for the Piazza del Duomo and there is a dome in the middle that is divided into eight segments. The most extraordinary piece of the Baptistry is the interior of the dome that is done up in Byzantine mosaic. The structure has 3 doors and the most significant one is the Gate of Paradise which was sculpted by a 22 year old artist Lorenzo Ghiberti.