R.F. O’Sullivan & Son (CLOSED)

Any connoisseur knows the “Boston’s best burger” dialogue has to include a mention of R.F. O’Sullivan’s. The bare-bones tavern is an old friend to carnivores who crave simply delicious patties topped with such accoutrements as spreadable blue cheese, barbecue sauce, or bacon, tomato and coleslaw—almost 30 varietals in all. The beer list gets the job done, but teetotalers will appreciate the massive root beer float.