He was snared by police after a photo of him urinating on the steps of Basilica di Santa Maria del Fiore, a UNESCO World Heritage Site completed in 1436, was posted on Facebook, according to a report in Corriere Fiorentino.
The picture then made it to the front page of a local newspaper, enabling police to identify him through the social network.
Though he has not been named in the Italian press, Corriere reported that he hails from the town of Montelupo Fiorentino.
He reportedly apologized to police, saying he did not mean to offend the church or city of Florence and that he committed the indecency "while in the grip of the fumes of alcohol".
Authorities in Florence come down hard on anyone caught debasing their city, the birthplace of the Italian Renaissance.
In October, a 27-year-old woman from Turkey was told to clean Ponte Vecchio and fined €160 for vandalism after attempting to scrawl names on it with her nail polish.
The incident came just a week after a German tourist was told to do the same after his daughter drew stars on the bridge with a felt-tip pen. He was also hit with a €160 fine.