Florentina was established in Roman times as a settlement for veteran soldiers. The name had changed already when young Charlemagne conquered the town in 774. It became part of the Duchy of Tuscany, with Lucca as the capital. Around 1000 Margrave Hugo chose Florence as residency instead of Lucca. After the death of Matilda of Tuscany (1115), the Florentines formed a republic ruled by a council. The town prospered, despite a constant fight between the different factions and noble families.

In the 15th century, Florence was among the largest and wealthiest cities in Europe. This was when the Medici family entered the political scene. As a dynasty of art-loving, power-hungry bankers, they made Florence the birthplace of the Renaissance.
The Baptistery of San Giovanni is the baptistery of Florence Cathedral. The time of origin is disputed, the church was consecrated in the 11th century. The church stands on the foundations of a Roman building. The first reliable source dates from 897, when an ecclesia (church) dedicated to John the Baptist and facing the bishop's palace is mentioned.

Today's building dates from the 11th century at the earliest. The octagon had been a common shape for baptisteries for many centuries since early Christian times. The construction was finished in 1128. An octagonal lantern was added to the roof around 1150. It was enlarged with a rectangular entrance porch in 1202, leading into the original western entrance of the building, that in the 15th century became an apse, after the opening of the eastern door facing the western door of the cathedral by Lorenzo Ghiberti.

Between the fourteenth and sixteenth centuries, three bronze double doors were added, with bronze and marble statues above them.