Pisan calendar

This is the reason that most dates have an apparent discrepancy of one year, as the two calendars differ for just over nine months of each cycle.

By contrast, calendars in the stile della Natività ("style of the Nativity") as in Arezzo, Assisi and Perugia began on the Solemnity of the Nativity of the Lord (Christmas) on 25 December, the Venetian calendar began on 1 March until the Fall of the Venetian Republic, and the French year on Easter day until 1564.

The traditional Julian calendar was sometimes said to be in the stile della Circoncisione ("style of the Circumcision").

Not until 1749, however, were the ancient calendars definitively outlawed in Tuscany: in that year the recently appointed Grand Duke and Holy Roman Emperor, Francis I, ordered that, starting from 1750, the first of January should become the first day of the year, thus having the "peoples of Tuscia" conform to all the others.

A plaque in Latin commemorating the grand ducal/imperial decree is affixed to the west wall of the Loggia dei Lanzi, in Piazza della Signoria in Florence.