Friends with a home outside of Rome had told me on my first trip to Italy, that one of the crown jewels of visiting Tuscany would be to spend the entire day in Siena. Really? A whole day? Yes they said. You will go to the Duomo Siena and be AMAZED.
I had been to many big cathedrals; Chartres, Notre Dame, National Cathedral in Washington D.C., Grace Cathedral in San Francisco, etc. But truly, the Siena Duomo is one of the most magnifcant buildings, second only perhaps to the Vatican. The floors are covered with inlaid marble scenes, the columns covered in stripes seem to go on forever, the walls have sculptures that jut out of them (all the heads of the Popes!), carved wood, painted wood, catacombs, monstrous chandeliers, and a library with illuminated manuscripts. I've studied art my whole life, I would not joke about what a marvel, what a discovery this place is.
Get an Opa Si pass, spend the day. When you are tired or hungry, walk down to the PIazza del Campo and just sit, eat, enjoy gelato or coffee. People watch. Here is where you will feel yourself become an Italian, if only for a day.