I have been lucky enough to time my journey with this incredible party. We arrived at the station at 12.30h. There is a walk to the village center. Once there we ate early so we could be in the square before 5 o'clock. While we were eating the parade began. Each neighborhood has a flag and a rider. They march through the streets of Siena showing off. In the central square set-up like a bullring they closed all entrances and exits because the parade begins (flags, horses, music, etc ...) The big race begins at 7 o'clock. But beware, there is one draw to determine the order of the horses. To start the race all have to be insane (which is not easy because that means all of them) and that the race is valid one also has to be ahead of others. It was exciting but the problem is that the last train left at 21.17 and at 20.30 we were still there. You can not imagine the run that we did in order to catch the train. I liked it but it but it was a pain as well as being really hot.