Halfway between Florence and Siena, in this wonderful strategic position, today we are going to visit Poggibonsi. A city rich in history, within the Elsa Valley, nestled in the Chianti hills. Let's go and visit it now! We note the imposing complex of the Medici fortress of Poggio Imperiale, a symbol of the city. Built in 1500 by the will of Lorenzo the Magnificent, in reality it was never finished. Instead, the Cassero was completed, which offers us enchanting views of the Tuscan countryside. This imposing and marvelous work, with a pentagonal plan, takes up the anthropomorphic form theorized by Francesco di Giorgio Martini. The remains of the medieval settlement of Poggibonsi are clearly visible, inside what is now the technological archaeological park of Poggio Imperiale. We still visit the Costantino Marmocchi Museum, inside the Palazzo Pretorio. In the historic center we can also admire numerous fossils that testify to a marine past of the city, dated about two million years ago.