San Giovanni square is the spiritual heart of Florence, even before Chistianity became the main faith in Florence. At that moment, the Cathedral could be established within the city walls, it was changed from ancient San Lorenzo to Santa Reparata, in the same spot of Santa Maria del Fiore. The baptistery, the cimitery and the hospital were built in the same square, a rich spiritual area for ancient Florence since the Fifth Century.
The history of Florence foundation dates back to Roman age. Florence was a Roman “castro”, a war settlement. Since then a roman society flourished from the castro and there must have been a religious center, as any roman town had.
Archeologists suppose that it was in the area where is the Cathedral now. For several years they thought the Baptistery was built right on the plant of the ancient altar to Mars divinity. Recent studies couldn’t find any document of Mars altar, but untill Middle Ages a statue near Arno River was considered to be a Roman monument to Mars: it was never destroyed because citizens didn’t want to lose his favours. It is reported that the monument was covered with mud or flowers depending on the harvest of the year. The monument got lost in a river flood in 1333.
The majority of Italian towns witnesses previous cultures subistituted by modern, and most of them were previous roman centers.