It consists of three laps around the piazza, with the first horse to complete the laps winning regardless of if its rider has fallen off during the race!
The Palio di Siena is a very old tradition in Siena, dating back to beginnings in 1633. The piazza has long been a source of public entertainment, historically hosting games, jousting matches, and bullfights. After bullfighting was outlawed in Siena, it became common for public races to be hosted in the Piazza del Campo. Eventually bareback horse racing became popular, and the Palio was born! Today, it is also a source of pride for the contrada (similar to a neighborhood). Siena is home to 17 contrada, with each Palio hosting riders from 10 different contrade (the plural of contrada). Winning is a large source of contrada pride, and a list of years that they won the Palio is often displayed in the contrada's museum.
The Palio di Siena is highly connected to the environment of the Piazza del Campo. The large sloped interior provides a safe, designated area for viewing the race. The large paved edge provides the perfect setting for a horse race, and the scalloped shape of the Piazza del Campo allows the race to circle around the viewers. Additionally, bollards (short stone pillars) border the edge of the piazza interior, providing a safe boundary between viewers and horses during the race. This tradition is directly shaped by its environment.