Jockey Giovanni Atzeni (L), known as Tittia, rides his horse bareback on his way to winning the Palio dell&#39;Assunta horse-race at Piazza del Campo square on August 16, 2013 in Siena, Italy. The Palio races in Siena, in which riders representing city districts compete, and takes place twice a year in the summer in a tradition that dates back to 1656.