Porta San Pietro: We find it hidden among the trees before entering the spaces of the Stampace bastion, of which it is part. Unfortunately, it is completely abandoned, but part of the large pointed arch and the shelves on which it rested are clearly visible.The cannonballs: the 'people's war'. Thus in the 16th century the episode of 1499 was known throughout Europe. It left its traces right in the walls beyond the Stampace bastion, in via Nino Bixio. Looking out over the external side, near the interruption of the medieval layout, we can still see grey stone ballsset between stones and bricks: they are the cannon balls used by the Florentine militias to make a breach, placed by the Pisans to decorate the walls in mockery of the enemyGiorgio Vasari, in the hall of the Cinquecento of Palazzo Vecchio in Florence, painted the taking of Pisa (1563), an episode that immortalises the mighty bastion from which the old fourteenth-century tower rises, called Stampace (star in pace - be in peace, possibly used as a prison). The painting represented the power exercised by the Medici, in particular of Cosimo I, over Pisa. In reality, the episode represented was a big fiascofor the Florentine militias, since it refers to the Siege of Pisa and in particular to 10 August 1499. Pisa, freed from Florence in 1494 by King Charles VIII of France, resisted the attack thanks to the help of Lucca and above all to the intervention of women and the elderly. That date therefore represents a defeat for Florence (the peace agreement between the two cities was signed only in 1509). In the 17th century, during the government of Cosimo III, the bastion was further strengthened by adding an embankment structure. In the 19th century the bastion became part of one of the first railway systems of the city: a platform for the turning of railway wagons was inserted in the building.