Siena, located in central Italy's Tuscany region, is known for its ancient brick structures. UNESCO has designated Siena's historic center as a World Heritage Site. It is one of the most popular tourist sites in the country, with over 163,000 international visitors in 2008. Siena i… Siena, located in central Italy's Tuscany region, is known for its ancient brick structures. UNESCO has designated Siena's historic center as a World Heritage Site. It is one of the most popular tourist sites in the country, with over 163,000 international visitors in 2008. Siena is well-known for its cuisine, art, museums, medieval architecture, and the Palio, a twice-yearly horse race.