Baptistery of San Giovanni

Dante was baptized here. So was every other Florentine born between the eleventh century and the nineteenth. For nearly a thousand years, this octagonal building was the sole baptismal church of the city — if you were Florentine, your life began at its font. The structure dates to at least the fifth century, possibly earlier, and medieval Florentines genuinely believed it had been a Roman temple to Mars.

The real stars are the doors. Lorenzo Ghiberti spent 27 years on the east doors — from 1425 to 1452 — creating ten gilded bronze panels depicting Old Testament scenes. He used 34,000 pounds of bronze and the project cost 22,000 florins. When Michelangelo saw them, he reportedly declared them worthy of being the "Gates of Paradise," and the name stuck. The 17-foot-tall doors weigh four and a half tons. What you see on the building now are replicas — the originals were moved to the Museo dell'Opera del Duomo for preservation.

The north doors are also by Ghiberti, commissioned after he won a famous competition in 1401 against Brunelleschi. That competition is often cited as the starting gun of the Renaissance — two young artists battling over who could better depict the sacrifice of Isaac, and the loser going off to study Roman architecture and eventually inventing the dome across the square.

Step inside and look up. The ceiling is covered in Byzantine-style mosaics from the thirteenth century depicting the Last Judgment, with a terrifying 8-meter-tall Christ in the center. Dante saw these mosaics as a child, and scholars believe they influenced his vision of Hell in the Divine Comedy.