Located northwest of central Siena, it is also known as Forte di Santa Barbara.
This fortress was designed by military engineer Baldassarre Lanci on a 1560 order of Cosimo I de’ Medici of Florence to station his garrison force.
The inner courtyard is now called Piazza della Libertà. It is used for special exhibitions.
Our local tour guide never mentioned the period when Siena was ruled by Florence. We walked by this fortress on our way from Basilica of San Domenico back to the tour bus.