The "Palio" horse race is more than just a simple medieval feast as there are many others around Tuscany, many of which seem to be more of touristic events to generate more visitors.
Of course Siena is mobbed during the week of the Palio by curious tourists, but the Palio is strictly a Sienese tradition for the Sienese people.
The race takes place twice a year on July 2nd and August 16th. The week that precedes the Palio is a week of anticipation in the Contrade neighboorhoods that will run the race, where the Contradaioli (people who belong to the neighboorhood) will socialize in the evenings with common meals in the streets decorated with the flags and colors of their Contrada. It's very colorful to see and the atmosphere is festive and exciting.
There are daily trial runs in the Campo before the actual race that are nice to see, because it is less crowded that the actual Palio.
The winner of the Palio receives the "Palio" which is a flag especially made for the occasion by commissioned artists. In this video you will see the Selva Contrada marching the streets the day after the Palio, showing off their winning horse and the Palio flag: