If you are a first time traveler, stick to the Rome-Florence-Milan-Venice circuit. If you have done that already and want to discover Italy, Siena is a great place to visit. You will see this piazza where in July and August the world famous Palio di Siena happens (horse race around the square, and each horse represents a neighbourhood). And where capitalism started. And where the colour "Terra di Siena" comes from. By all means, this is a must see place. There is not really much to see if you are an attraction-type-of-person, but there is a lot to discover.
You can park in one of the recommended sites and there was a sequence of (free) escalators that took us to the old city. What a treat.
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