Markets in Rome

Markets in Rome usually open at 7am - 1pm, Monday to Saturday.
Campo de Fiori
Often mentioned in the guidebooks as a quaint, sometimes must see, market within easy reach of nearby tourist attractions. Translated literally as Field of Flowers, the Field refers to the fact that the area was a field until the 15th century when it was paved over.
Getting there: It is a 9 minute walk from the Pantheon and 5 minute walk from Piazza Navona

Porta Portese
Vendors are likely to sell merchandise ranging from secondhand paintings of Madonnas and termite-eaten Il Duce wooden medallions, to pseudo-Etruscan hairpins, rosaries, 1947 TVs, and books printed in 1835. Serious shoppers can often ferret out a good buy. If you've ever been impressed with the bargaining power of the Spaniard, you haven't seen anything until you've bartered with an Italian.
Getting there: Bus: 75 to Porta Portese, and then a short walk to Via Portuense
Opening Hours: Sunday 7am - 1pm
Reference: http://www.frommers.com/destinations/rome/S23959.html

Piazza Vittorio Emanuele
The largest open-air food market in Rome takes place at Piazza Vittorio Emanuele. Most of the vendors at this gigantic square sell fresh fruit, vegetables, and other foodstuffs, although many stalls are devoted to such items as cutlery, clothing, and other merchandise. The place has little to tempt the serious shopper, but it's great for discovering a slice of Roman life.
Getting there: Metro: Vittorio Emanuele, 9 minutes walk from Termini
Reference: http://www.frommers.com/destinations/rome/S23958.html