In no particular order:

Delmonico's, New York
The first full-fledged restaurant in the U.S. was founded by a Swiss sea captain named Giovanni Delmonico in 1837 down in the then-burgeoning Wall Street district, with individual, well-set tables, French wines, an à la carte menu, and a lady cashier. Every important personage and famous visitor, including Charles Dickens and William Makepeace Thackeray, dined at "Del's," and Samuel F.B. Morse sent the first transatlantic cable from a dining room. Over two centuries, Delmonico's moved uptown (and closed during Prohibition), but the Beaver Street restaurant, with its marble portals from Pompeii, is still going strong. Along with a steak-and-chops-heavy menu, you can still get Oysters "Diamond Jim Brady," and the original Lobster Newberg and Chicken a la Keene.

Durgin-Park Café, Boston
Opened in 1827 in Faneuil Hall Market, Durgin Park still has long, communal tables, tile floors, waitresses known for their sass, and true New England food, from a singular clam chowder to Yankee pot roast with cornbread, from baked scrod and fried Ipswich clams to molasses-rich Indian pudding and chocolate-topped Boston cream pudding. Good New England beer selection, too. (Come in the back door to avoid the crush of tourists coming in the front.)

Antoine's, New Orleans
In 1840, Marseilles-born Antoine Alciatore opened his big namesake French restaurant on the Rue St. Louis, and it has survived the Civil War, Prohibition, and Hurricane Katrina. Local food writer Gene Bourg insists, "New Orleans without Antoine's would be like Giza without the Great Pyramid." It was here that oysters Rockefeller were created, and longtime patrons claim not only their favorite rooms among the fourteen at Antoine's, but even their favorite waiters. Don't miss the shrimp rémoulade, the chateaubriand with marchand de vin, the pommes soufflé, and the famous and flaming baked Alaska.

Griswold Inn, Essex
Having been in this quintessential Connecticut colonial town since 1776 — and serving Washington, Mark Twain, Einstein, and Kate Hepburn along the way — "The Gris" serves the same classics that whaling captains probably ordered when it opened — lobster pot pie, cod, unimpeachable clam chowder, and summer corn. The look of the place — the general lineaments of worn wood, tilted ceilings, creaky floors, old maps — probably hasn't changed much either, thank goodness. In the Tap Room: beer, free popcorn, and whatever banjo player or swing band is on the slate that night.

Buckhorn Exchange, Denver
Around since 1893, the Buckhorn Exchange is as much a museum of western artifacts as a restaurant specializing in game, from buffalo and alligator to rattlesnake and Rocky Mountain oysters, along with terrific T-bones and "Gramma Fanny's pot roast," all on the menu since Buffalo Bill, Roy Rogers, and Ronald Reagan ate there.