The piazza is small giving a very intimate feel. The Fountain of the Four Rivers stands in the center of it surrounded by street performers at night. Across one side is a strip of restaurants and, yes, they also serve gelato.
Here's the street view.
As we left, we took a taxi. Unlike the other traffic, our taxi driver was stopping at every red light. I asked him why, joking that he just wanted to make the meter run. He said that he wouldn't stop if I'd pay his fine. I laughed and said I would. He proceeded to run every red light all the way back to the hotel.
The wikipedia article is here.
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