Bonci Pizzarium
This tiny storefront by famed pizzaiolo Gabriele Bonci is the city's most famous place for pizza al taglio (by the slice). It serves more than a dozen versions, from the standard margherita to slices piled high with prosciutto and other tasty ingredients. There's no seating, but you can stand at one of the tables outside. Avoid peak hours or be prepared to wait up to an hour.