A little North End in North Cambridge
Replicating the authenticity of Rome isn't easy to nail, unless you're talking about HBO's version, where apparently everything is nailed with very little effort. For a Cambridge spot getting the city's food right: L'Impasto.
The first solo bid from the legitimately Roman former chef of North End highlight Ristorante Fiore, L'Impasto (which translates loosely and made-uply as "limp pasta") is an authentic-as-it-gets Italian eatery peddling fresh handmade pastas and breads in a quaint 20-seater that welcomes guests with an open kitchen, an intimate two-table sidewalk patio, and hung kitchenware, which, ladies will love even more than normal kitchenware. Classic noodles include bucatini w/ Italian bacon in a white wine tomato sauce, clams and broccoli rabe tossed w/ olive oil & gnocchetti sardines, and pappardelle covered in a zucchini sauce w/ baby shrimp, also the name of the pop song that has mad crustacean tweens crushing on Bieber. Assuming you already had spaghetti for lunch, they're also slinging pizzas like a prosciutto/ zucchini/ smoked mozzarella white plus noodle-less classics like a balsamic smoked salmon with olives & fennel, and veal scaloppine w/ sage, whose wisdom apparently wasn't enough to keep it from getting eaten.
To round things out, LI hawks to-go breadbaskets overflowing with fresh-baked anchovy loaves and prosciutto-topped focaccia, and for dessert, serves a wild berry tiramisu so decadent, it could be on HB -- oh, god... are they really showing that?