A famous social center, this square is lined with restaurants and cafés which make good (though not necessarily cheap) candidates for lunch. The best known is of course Le Tre Scalini, where you can enjoy a nice plate of gnocchi while people-watching around Bernini’s famous Four Rivers fountain. For dessert, you can stay and treat yourself to some of Tre Scalini’s renowned tartufo chocolate-ice-cream concoction, or stroll several blocks north and east to Giolitti, a historic gelateria (ice cream parlor) that serves some of the best gelato in Italy.
Read more in my post Rome in One Weekend? Sì, Signori!