The iconic bistro/cafe that's been popular since long before Hemingway, Picasso, Sartre, and their ilk chain-smoked and binge-drank their way through their croque monsieurs. Just as epic is Magot's friendly long-standing (since the 1800s) rivalry with neighbor Café de Flore. They're both super touristy, but still super cool.
6 Pl. Saint-Germain-des-Prés