Oggi's is a great Italian neighborhood eatery here in the Northwest/West Loop part of Chicago (at Grand and Noble for you locals). Aside from their extensive menu of pasta, panini and killer apps (the calamari in particular), they make what I consider to be some of the best pizza in the city. They do the whole thin/deep-dish/stuffed thing that most good Chicago pizza joints do, and they're all very good. However, having never really bought into the whole "Chicago style" pizza myth, it's the authentic Italian thin crust pies Oggi's makes that I truly love.
Aside from the classic ingredients (no yuppie toppings like tofu or asparagus here, folks) Oggi's has as regular "specials" on their menu: truly traditional Neapolitan pizza! The two styles listed are the Margherita (sliced tomatoes, basil, olive oil, mozz. and romano cheese) and the Siciliana (rustic sauce, anchovies, garlic, basil, mozz. and romano cheese). You can also gain respect by asking for a pizza Romana (a Margherita without tomatoes) or a plain ol' Napoletana (sauce, anchovies and mozz. cheese) though they're not on the menu.
The crust is PERFECT: a bit burnt 'round the edges, very crispy, and not too "yeasty". As for thickness, it's "medium" thin and hand pressed for a perfectly imperfect consistency, but if you prefer razor thin crust, just ask for it. Plus, they cut the pizza in wedges and not all the way through which is the way Italian pizza is supposed to be served, if not cut at all. One note: if you have an Oggi's pizza delivered, the time spent in the box will soften the center a bit which is unavoidable. For the best experience, grab a table and eat right there. Add a cold beer (yup, they carry Birra Peroni, an Italian beer) or a glass of wine and you're good to go.