Marché aux Puces de Saint-Ouen (Flea Market) is a real time commitment — fit it in only if it's a priority.
Allow 2–3 hrs.
A sprawling warren of antique dealers, vintage clothing and bric-a-brac that rewards browsers and bargain hunters. It's a bit out of the way and the immediate area is rough around the edges, but for collectors and the curious it's a unique half-day. Weekends only.