Bustling market by day and social hot spot once aperitivo hour hits, Campo de Fiori is well-positioned to be the public square you return to numerous times during your visit. A few blocks south of the over-touristed Piazza Navona, the market is a mixture of fruits and vegetables and the tourist-related stalls that thrive in this central part of Rome; if you value the authenticity of a locals-only market, then you ought to head elsewhere. Then again, you can still find a few good deals and the brooding figure of Giordano Bruno, burned at the stake for heresy, lends a pleasantly foreboding air to the proceedings.
Once the market closes around 5pm, things stay busy at the numerous beer and wine bars that fringe the large square, making it an excellent area for aperitivo or late-night socializing. You'll find that, like everything in the central districts of Rome, food and drink are quite expensive. If anything, head a few blocks south to the much more placid Piazza Farnese for somewhat cheaper eats and laid back vibes.
Note:The Forno bakery and Grom gelateria come highly recommended.