The cheapest traditional market in the port area. Vendors come from all around. You pay like two times less than in a supermarket. Smells, colors, sounds, chaotic movement makes this crazy and authentic, though not very safe for gringos.
To feel what is Brazilian traditional market, to buy authentic souvenirs which are not souvenirs but useful things in a household, Candomblé ceremonies etc. All kinds of fruits, meat, fish, crafts, herbs and liquids.
Have a lunch in one of the stree restaurants there!