Rome's main Sunday flea market is at Porta Portese in Trastevere
The mother load of Roman bazaars is Porta Portese, a flea market off Piazza Ippolito Nievo that began at the close of World War II as a black and gray market but has grown to be one of Europe's premier permanent garage sales with more than 1,000 stalls and exhibitors.
You'll find everything here from antique credenzas to used carburetors, bootleg CDs to birds that squawk "Ciao," previously owned clothes to Italian comic books to used Leicas, all in a carnival atmosphere of haggling and hollering, jostling and junk jockeying, beggars, pickpockets, and shrewd stall owners, swirling around auditory pockets of badly dubbed dance music and the the scents of sweet roasting corn.
It runs every Sunday, from soon after dawn until late lunchtime.
Hang on to your wallet (not because of the prices; becasue ot the pickpockets)
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Even if you just want to take a quick peek, it will probably take an hour to find your way out again. Shoppers will spend 2-3 hours here.
Seriosly, hold on to your wallet. Crowded markets like this are prime hunting grounds for light-fingered Luigis.