Amid the swank food sanctums sprouting around Park Avenue South, this classic tavern remains a shrine to unchanging values. Most old-time Old-Towners go for the much-praised burger, which we found in need of a little salt. For lightweights, there’s a smattering of salads and other sandwiches. Some things, however, do change. Bloomberg’s antismoking legislation has made the once befogged booths and long mahogany bar strangely haze-free.