The Rocca di San Paolino was a medieval historical-architectural complex of strategic military importance as a Pisan outpost in the struggle against Lucca. It is a fortification with irregular polygon formwork and three towers with small square limestone ashlars, the same adopted for the construction of the medieval walls of Pisa.
In the 15th century was further fortified to withstand the impact of firearms, thanks to the work of the architect Giuliano da Sangallo. Even today you can see the difference between the original part and the following one.
When the town lost importance as a strategic military bulwark, the fortress was unfortunately left to itself. On the access door you can still see the coats of arms of the Pisan and Florentine mayors, while of the old towers remain that of Centino and Niccolai.