Laura Reiely, the restaurant critic for the St. Petersburg Times, has a list of 25 iconic restaurants that are at least 25 years old: http://www.tampabay.com/features/food.... The only real glaring omission, imho, is Mise en Place, though it might be under 25. Otherwise an excellent list and a fun time debating them.
And I can't believe I had never heard of, much less ever visited, Biff-Burger. What other worthy restos were left off the list?