The Baptistery of St. John is one of the monuments that make up the Complex of the Cathedral of Florence, along with the Cathedral of Santa Maria del Fiore with the Dome of Brunelleschi and the excavations of Santa Reparata, the Baptistery itself, Giotto's Bell Tower and the Museum of the Opera del Duomo.
Structure consecrated in 1059 by Pope Nicholas II and dedicated to the patron saint of the city, St. John the Baptist. The construction of the building began around the fourth century AD, on the ruins of a Roman domus.
In 1128 it officially became the Baptistery of Florence and in the following decades the external marble cladding, the marble inlaid floor and the dome were made, completed in the middle of the 13th century.
Splendid mosaics with a golden background decorate the dome and apse of the Baptistery: arranged in concentric circles, they represent the angelic hierarchies, the stories of Genesis, the stories of Joseph, the stories of Mary and Christ, the stories of St. John the Baptist, and finally the famous Last Judgment, attributed to Coppo di Marcovaldo.