They're known for their fish and their carbonara, but we went bucatini amatriciana, fettuccine with mushrooms, and trippa alla romana. The food was cozy, peasant-like. Bonus: the waiters gift you little plates of delicious (albeit salty) things, like beans, croquettes, and even pasta (!), while you wait for your dinner. We got lucky and were seated by the windows (make reservations) and got to see Roma grow dark.
You know what the perfect thing to do after dinner at Hostaria Romana is? Walk to the Trevi to see it glow: