The Fortezza Vecchia was raised on demand of the Florentine Government that started to plan this building after buying Livorno from Genoa in 1481. The aim to build it is to protect the port that the Medici destined to become the Florentine counter-attraction to Pisa's port of call.
The works started in 1506, when the architect Antonio da Sangallo was called in Livorno to plan a fortification project that could include two pre-existent Pisan structures, the Mastio di Matilde and the Quadratura. The Cardinal Giulio de' Medici, the future Pope Clemens VIII, was given the task to follow the operations in a first time. The works were interrupted between 1526 and 1530 and then the Grand Duke Alessandro started them again after suppressing the anti-Medicean revolt with the aid of the Spanish troops.
In 1543, Cosimo I ordered the construction of his residence, which the bombardments of the Second World War unfortunately destroyed, on the Fortezza Vecchia. Soon, the building also became a point of reference for Spanish ships.
In 1563, for instance, Fortezza Vecchia became the logistic support of the Spanish galleys that sailed to help Orano, besieged by the Turks. In 1601, instead, Maria de' Medici sailed from the Fortezza towards France to marry Henry IV.
With the dynasty of the Hapsburg-Lorraine come to the throne of the Tuscan Grand Duchy in 1737, the functions of the Fortress changed. Since it was not used as a defensive residence (Pisa was a town of the Grand Duchy, already, and pirates did not infest the Tyrrhenian any more) it was adapted to be a military college since 1769. In 1795, it also became the base of a barrack. In the following years, numerous apartments were created from its rooms.
The story of the Fortezza Vecchia is characterized by weird episodes. It is said that Cosimo I killed his son Garzia, who had murdered his brother, inside the complex. Actually, chronicles tell that both the Grand Duke's sons died of a fever contracted during a battue. Another strange fact took place in 1734, when after a violent storm the inhabitants of Livorno found a 7 metres long whale, dragged there by the current, at the foot of the fortress.