One of the oldest streets in Paris, the Rue Mouffetard tumbles downhill from the Place de la Contrescarpe through the heart of the student quarter, cobbled and crooked and lined end to end with food. The lower stretch is a near-permanent market — cheesemongers, bakers, greengrocers, fishmongers, a roast-chicken stall or two — while the upper end runs to crêpe windows, cheap restaurants, and the kind of small bars that fill with Sorbonne students at night.
It is the most concentrated dose of Latin Quarter atmosphere going: noisy, cheap, and unpretentious. Come hungry, graze your way down, and don't expect haute cuisine — that is rather the point. Markets and shops are liveliest in the morning; much closes on Monday.