Driving along the highway that goes from Florence to Siena, when you get near Poggibonsi, you can see an imposing crown of walls at the top. These walls make up the external perimeter of a Medici fort, which was built at the start of the 1500s by Lorenzo the Magnificent. The project was never completed and the small town planned inside the fort was never built. Instead, the pentagonal shaped Cassero was built and it is this recently restaured construction which rises above the surrounding Tuscan hills.
The whole peak of the Poggio Imperiale hill, which looks over the town of Poggibonsi has played a major role in the history of human settlement in central Tuscany.