The area of the Lungarno Simonelli is dominated by a tower of the thirteenth century, an ancient fortress built on the riverbank of the Arno by Florentines in 1405, close to the arsenal of the Pisan navy which communicated with the sea through the Arno river and a channel.
Under the Medici, the old republican arsenals were chosen as headquarters of the Medicean fleet.
With the transfer of shipbuilding to other venues and due to the unexpansionist policy on the sea by the Medici, the arsenals suffered a gradual decay.
Even the Cittadella lost its military function. In the 8th century, the building became a prison; the next century served as a barracks and in the eighteenth and nineteenth centuries the arsenals were turned into stables. The structure of the arsenal today is home to exhibitions and conferences. In the citadel are kept weapons and costumes of the participants of the Gioco del Ponte: an historic game that takes place every year on the Ponte di Mezzo, the last Sunday of June.