Palio mentality and what to expect
The twice per year Palio horserace in Siena attracts hordes of tourists, and is part of the reason why Siena is a major holiday destination in Tuscany. Around the Palio, if you think you're coming to Siena for any other reason than the Palio - pick another week. Visitors might want to understand that the Palio is more than a lucrative festival for the people of Siena. It is taken very seriously, to the point of being somewhat alienating for anyone not born and bred in Siena. The Palio is not for the tourists, nor for fellow italians - it is senese identity and culture, and as such rather difficult to comprehend beyond the obvious show. It represents one of the very few truly authentic festivals with a historic legacy, and has remained largely unchanged for many centuries. Thus, while the massive presence of visitors is tolerated rather than encouraged, little in the way of guidance for the casual visitor is provided. Expect crowds, parades with drumming and chanting all over town for days on end, trial races, and a lot of other ritual events. Everyone who belongs knows where to go and when. If you don't want to find yourself clueless, be prepared to do some serious reading up, or make sure to hang out with someone who's in the know. A testimony to the seriousness of this event is the historical enmity between the factions. All but one have a dedicated "enemy", and nearly as important as winning, is not losing to the enemy. There are regular brawls between factions in these days, and all the factions have muscle to defend their honor. There is hardly any risk for outsiders, but do understand that there is a violent aspect of the event.
As for the actual main race, a few quick facts to prevent undue frustration. If you're not already in Siena, forget about coming here by car. Finding a parking spot is absolutely impossible. Moving around town is a slow affair, and walking is your best bet. Approach the piazza in time, and expect some pushing and shoving to get in. The closer to the start, the slower you will advance. If for some reason you change your mind about the whole affair and want to leave, moving against the crowd, you won't be very popular. The best spots in the piazza are "conquered" by contrada (city districts/factions) members the night before. Try to maneuver into a high spot so that you can see at least part of the race track. If you're shortish you really have to find a good spot. Factions are gathered in groups around the piazza, and you might not want to be right in the middle of one (nor do they want you there). The race is preceded by the so-called historical parade, which starts at the duomo and gradually arrives at the piazza. This lasts for some 3-4 hours total. Access to the piazza is closed about 30 min before the estimated start of the race. At that point, you can't get out short of a medical emergency. In fact, moving around is rather laborious. There are no facilities once you're in, you can't buy food, there are only a few places where you can buy drink, tens of thousands of people around you, and possibly still very warm. The start can be a quick or long affair, depending on how stressed out the horses are, and the degree of foul play between the jockeys. Once the order is called out jockeys will begin to offer bribes for assistance between each other. What you're waiting for is that they finally line up in the proper order, facing the right direction, without causing too much of a racket. Once that happens, the rope will fall as a gunshot is heard. This can happen fast and unexpectedly, after you've seen up to an hour of failed attempts, or rather early. The race takes little over a minute and is fast and furious. Horses and riders regularly fall, sometimes nastily. The crowd is wild not to say hysterical, so expect some serious display of emotion. Once the race is over, prominent members of the winning factions grab the Palio (a banner, made by a new artist for every race) the winning horse is taken to the church of Provenzano (in july) or the Duomo (in august), where the Madonna is thanked for the victory. Then, whoever wants converges on the winning contrada where victory is celebrated throughout the night. Don't expect to get much sleep if you're staying in the centre during these days.
All in all, the whole event is kind of hardcore, anything but comfortable or convenient, requires patience and persistence, and may not be for the faint of heart (physically or emotionally). In turn, you get to experience something pretty unique and most genuine.