Don't leave Rome without sitting down to a Roman pizza in a pizzeria. Yes, pizza may have been invented somewhere else, but in Rome you can hardly walk a block without passing it in one form or another. Look for a place with a forno a legna (wood-burning oven), a must for a good thin-crust, plate-size Roman pizza. You can also find places that prefer to serve a thicker-crust, Neapolitan style pizza ("alta"). With either option, tradition is the rule: don't look for pineapple or barbecued chicken among your topping options, nor should you ask for peperoni and expect a salami -- in Italian, it means (sweet) pepper. Instead, expect crispy pizzas with sauce and cheese that are a cut above anything you've had elsewhere.
Standard models are the margherita (tomato, mozzarella, and basil), napoletana (tomato, mozzarella, and anchovy), and capricciosa (tomato, mozzarella, prosciutto, artichokes, olives, and a hard-boiled egg), but most pizzerias have a long list of additional options, including tasty mozzarella di bufala (buffalo-milk mozzarella).
Many small shops specialize in pizza al taglio (by the slice), priced by the etto (100 grams, about ¼ pound), according to the kind of topping (or endless combinations thereof) from which to choose. Most pizzerias are open only for dinner, usually from 8 PM to midnight.
The wine at a pizzeria is worth skipping; Italians drink beer with pizza. There are often other things to order on a pizzeria menu, including standard starters like bruschetta (grilled bread, usually topped with chopped fresh tomato, basil, garlic, and olive oil), crostini (toasts with toppings and usually melted mozzarella), and fritti (deep-fried finger foods) such as olive ascolane (breaded green olives with a meat stuffing) and supplì (rice and tomato-sauce balls with mozzarella centers). Here are a few good by-the-slice pizzeria choices:
Il Forno di Campo de' Fiori (Campo de' Fiori. 06/68806662. Closed Sun.) makes excellent pizza bianca and rossa all day. Due to its popularity, the pizza is always running out, and just as constantly, they're carrying in another meter of it, fresh from the oven.
Behind Piazza Navona, Lo Zozzone (Via del Teattro Pace 32. 06/68808575. Closed Sun. and Aug.) makes wood-fired pizza bianca. Fillings are spread out along the bar -- everything from ham and turkey and mortadella (the original thinly sliced bologna) -- so just point and choose to make a fantastic sandwich.
Panificio Renella (Via del Moro 15-16, Trastevere. 06/5817265) is Trastevere's best bet for bakery pizza and is one of the few places open on Sunday; lines throughout the day are a testament to its pizza makers' bravura. The pizza with cooked prosciutto, mozzarella, and rosemary is delicious.
Pizza alla Pala (Via del Pellegrino 11, Campo de' Fiori. 06/6865083. Closed Sun.) has thick-crust pizza with multiple toppings; try it ai porcini (with mushrooms) or piccante con pomodorini e prezzemolo (with chilis, cherry tomatoes, and parsley).
Pizzeria Vecchio Borgo (Borgo Pio 27/a, Vatican. 06/68806355. Closed Sun. and Sat. afternoon in summer) churns out piping-hot pizzas; try the boscaiola, with sausage, mushrooms, and mozzarella, or la bomba, a truly explosive concoction with chili peppers.