Established in 1884, P.J. Clarke's is considered "the Vatican of saloons" (at least by the New York Times). An after-work staple since before the Mad Men era, it was the spot where Buddy Holly proposed to his wife five hours after they met, and where they serve a patty Nat King Cole called "the Cadillac of burgers." It has now expanded to multiple locations, but the original spot on Third is where it's at.