O'Sullivan's is known around Boston for the best burgers. They are hand-made HUGE thick patties - not those frozen hockey pucks you get at most places. They are so thick that they'll tell you upfront that it takes 20 minutes to cook them! And, it is definitely worth the wait. Paired with their french fries - YUM! I've never actually been able to finish a whole burger - but it's not for lack of trying!