Also called the Loggia della Signoria, the Loggia was named the Loggia dei Lanzi when the Duke Alessandro de'Medici made it the camp of the Lanzichenecchi after the fall of the Florentine Republic.

It was the Signoria which commissioned a great Loggia for public use in 1350. The job was started by Orcagna, but continued and finished by Benci di Cione and Francesco Talenti only in 1382.

Made in Serena stone with acute pointed arches and bricks decorated by sculptures designed by Agnolo Gaddi, this taste for a clasical style is what characterises Florentine art of the time. Benvenuto Cellini's famous "Perseus" was installed under the Loggia, and in the central arch Giambologna's marble "Rape of the Sabine Women", which can be found next to "Hercules with the centaur Nessus" also in marble. The other statues at the back near to the walls came from the Medici villa in Rome.

On the façade of the Loggia, below the parapet, are trefoils with allegorical figures by Agnolo Gaddi of the four cardinal virtues (1383-1386). Their blue enamelled background is the work of Leonardo, a monk, while the golden stars were painted by Lorenzo de' Bicci. The vault, composed of semi-circles, was done by the Florentine Antonio de' Pucci. On the steps of the Loggia are two Marzoccos, marble statues of lions, heraldic symbols of Florence; that on the right is from Roman times and the one on the left was sculpted by Flaminio Vacca in 1598. It was originally placed in the Villa Medici in Rome, but found its final place in the Loggia in 1789.

On the back of the Loggia are five marble female statues, Sabines and a statue of a barbarian prisoner Thusneldo from Roman times from the era of Trajanus to Hadrianus. They were discovered in Rome in 1541 They had been in the Medici villa at Rome since 1584 and were brought here by Pietro Leopoldo in 1789. They all have significant, modern restorations.