One of the most beautiful piazzas in all of Italy is the Piazza del Campo in Siena. Beautiful by day and night, site of the Palio on July 2 and August 16 every year. A beautiful view can be had by climbing to the top of the Duomo.
Beyond the city center, lie the famous vineyards of Chianti. Castello di Brolio one of many but this one is very impressive.