Siena Piazza del Campo is historic center of Siena, Tuscany, Italy and is one of Europe's greatest medieval squares. It is renowned worldwide for its beauty and architectural integrity. The Palazzo Pubblico and its Torre del Mangia, as well as various palazzi signorili surround the shell-shaped piazza. The twice-per-year horse-race, Palio di Siena, is held around the edges of the piazza.