Paris' open air markets are fun places to buy food, but also good places to people-watch (or even people-meet). Each takes place on a different days, and each has its distinct character. These are some of the more central or well-known. But every quartier has its market.
Unfortunately, the actual market has closed. But shops still line the Rue de Buci itself, which curves around from the Boulevard St. Germain and almost back, so that you can leave the more touristy hustle and bustle of the boulevard for a more rustic stroll.
METRO: Mabillon.
This street has a tremendous amount of history - Ernest Hemingway used to write in a café at its top - but also one of Paris' livelier markets. Especially fun for students, since Censier, a major university faculty, is right nearby. I went there one year and used to walk up the steep street, buying bags of tangerines or tiny cooked shrimp, which I then would nibble on the way home.
Aside from the food stalls and bakeries, there are a number of student cafés and restaurants all the way up the street.
METROS: Place Monge, Censier-Daubenton.
French friends often recommended this as one of the better markets. It's certainly one of the biggest, and there's a small flea market there too.
METRO: Ledru-Rollin.
A long street near Les Halles. Its main attraction (beside being near several interesting areas) is that it's long enough and lively enough (on market days) to merit a slow stroll from one end to the other.
METROS: Etienne Marcel, Les Halles
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