Piazza del Campo is the principal public space of the medieval historic center of Siena, Tuscany, and is regarded as one of Europe's greatest medieval squares. It is renowned for its shell-like shape and its unique red brick pavement, which is divided into nine sections by white marble strips. These nine sections commemorate the 'Council of Nine' who ruled Siena during its golden age in the 14th century. The square is the site of the Palio di Siena, a world-famous horse race that takes place twice a year. During the race, the square is covered in a thick layer of dirt to create a track, and riders race bareback around the perimeter. The square slopes downward toward the Palazzo Pubblico (the town hall) and its famous tower, the Torre del Mangia, creating a natural amphitheater effect that makes it a perfect gathering place for the community.