The Baptistery, right before the Cathedral, is one of Florence's oldest architectural monuments and has a past cloaked in myth: in the Middle Ages Florentines believed it was an Ancient Roman temple dedicated to the cult of Mars.
The strong geometric aspects of the building's structure and decoration, as well as the use of white and Prato green marble, is a happy combination of Romanesque and Paleochristian architecture carried out in the 11th-13th centuries.
The sculptures and basreliefs on the exterior of the building, above the doors and on the door frames, are among the most important ever created in Tuscany: the massive bronze doors were created by Andrea Pisano (the current South Door, in 1336) and Lorenzo Ghiberti (the North and East Doors, created in 1427 and 1452 respectively.)
The last of these is the so-called Gates of Paradise, one of Ghiberti's most important masterpieces, uniting late-Gothic elegance and classical harmony. The original doors have been removed for restoration and a few of the restored panels can be found in the Museum of Opera del Duomo. The doors seen today on the Baptistery are exact copies.
The marble groups located over the doors where executed by Francesco Rustici, Vincenzo Danti and Andrea Sansovino. The intarsiated floor on the interior of the building (12th-13th century) and the stunning mosaics on the ceiling and apse both stand out. The ceiling mosaics were created between 1266 and the beginning of the 1300s by artists who had been trained in the Byzantine style in Venice alongside Tuscan artists like Meliore, Coppo di Marcovaldo and Cimabue, Giotto's master.
The tomb of Giovanni XXIII, the Antipope who died in Florence in 1426, was designed by Donatello and Michelozzo and can be found on the inside of the Baptistery. Donatello's remarkable wood Mary Magdalen was originally there, though it can now be seen in the Museum of the Opera del Duomo.