The monumentale complex of the Fortezza da Basso, built on the outskirts of a mediaeval city from a design by the great architect Antonio da Sangallo the Younger, with the help of Pierfranceco da Viterbo, is now the main exhibition centre in Florence, where all the most important trade fairs and shows are held.

A cyclopic building with powerful bastions bristling with turrets, full of narrow passages, parapet walks and secret passages, the Fortress of San Giovanni Battista (called after St. John the Baptist, the Patron Saint of the city), is also a wonderful example of Renaissance architecture: built on a pentagonal plan, the shape of a human figure can be perfectly inscribed within its perimeter. .

The facade of the outer walls is carried out in round diamond-pointed projecting stone ashlars, perhaps inspired by the coat of arms of the Medici family, who ordered its construction.

This sophisticated military machine, a splendid example of the celebrated Fortresses built by the Sangallo family, was constructed in record time in 1534, during the reign of Duke Alessandro and with the return to power in Florence of the Medici family after the dramatic seige of 1529-30.