Palazzo della Signoria, or Palazzo Vecchio, as it appears today, is the result of at least three successive building stages between the 13th-16th centuries: the actual construction of Arnolfo's palace, overlooking the square and placed next to the Loggia dei Lanzi; the first alterations in Republican times, and the later restructuration carried out by Vasari, after the coming to power of Cosimo I de' Medici, who moved into the palace with all his family.

Palazzo Vecchio's exclusive role as the political representative of the city gradually lost importance from 1565 for three centuries, being partly replaced by the Uffizi and the new Palace at Pitti, though it came to the fore again at the end of this last century: after the Lorraine family had been expelled from the city in 1848, it became the seat of United Italy's provisional government from 1865-71, when Florence was the capital of the kingdom of Italy, and housed the Chamber of Deputies (the Senate sat next door in the Uffizi, linked up by an overhead passageway above Via della Ninna). It was to return to its original function as the seat of the City Council in 1872.

Although the palace today contains the offices of the City Council, much of it can still be visited. The public can admire the Hall of the Five Hundred, the little Study of Francesco I and the four monumental appartments: the Quarters of the Elements, the Quarters of Eleonora of Toledo, the Residence of the Priors and the Quarters of Leo X, where the reception rooms of the mayor and the council that governs the city are situated today. The Hall of the Two Hundred is once more being used for the meetings of the City Council and therefore not always open to the public.

The collection of musical instruments has rarely been shown to the public (soon to be transferred to the "Luigi Cherubini" Conservatory and linked up with the nearby rooms of the Academy Gallery) and the Loeser Collection, on the mezzanine floor, are rarely open to public viewing. The Siviero Collection, much of it formed by works stolen by the Nazis during the last war and since recovered, was also exhibited here fore many years.