The ultimate corned beef sandwich is as elusive as ever, but Washington doesn't lack for delis, old and new. Here, a few highlights -- and disappointments -- culled from a week's worth of noshing around the city:

Artie's Harbour Deli Cafe (Georgetown), 3000 K St. NW, 944-4350. Hours: 7 a.m. to 7 p.m. Monday through Friday, 11 a.m. to 6 p.m. Saturday and Sunday. Prices: Sandwiches $1.95 to $5.95. Cards: American Express, Choice, MasterCard, Visa.

Despite the varied selection of sandwiches and salads at Artie's, the biggest decision is not so much what to order, but where to eat once you order. A diner might be hard-pressed to choose between the splashy cafe, with its raised platform seating, soft lighting and silver-teal-rose color scheme, and the deli's patio, which spills out onto the main corridor of the Washington Harbour complex, with its view of the fountains and, beyond, the Potomac River.

Foodwise, one of the best bets is Artie's roast pork loin sandwich, juicy slices of warm pork slathered with cranberry sauce and served in a mini loaf of your choice: fresh baked white, rye, honey-wheat or seven-grain bread. It's not too often you find a sandwich this tasty. Alternatively, opt for a loaf of scooped-out bread, filled with a Greek salad of feta cheese, tomatoes and peppers. The quiches are enormous, custard-like wedges. For a pleasant finish, try the ice creams, in flavors running the gamut from apple brown betty to chocolate raspberry.

Knickerbocker Deli (Capitol Hill), 308 Pennsylvania Ave. NW, 543-3636. Hours: 11 a.m. to 11:30 p.m. Monday through Wednesday, 11 a.m. to 2 a.m. Thursday, 11 a.m. Friday through 4 p.m. Sunday. Prices: Appetizers $1.75 to $4.95; salads, sandwiches and pizza $1.99 to $14.95 (for a large taco pizza). Cards: American Express, MasterCard, Visa.

With its green tile floors, ceiling fans and jars of horseradish on each table, the fledgling Knickerbocker Deli has an authentic look. And when it's busy, this tiny, clamorous dining room sounds like the genuine article, too.

But the all-encompassing menu, which offers specials of calamari and spaghetti along with such standard dishes as sandwiches and pizzas, is pretty lackluster: A combination sandwich of corned beef, pastrami, turkey, cheese and Russian dressing wasn't any better for its commercial-tasting coleslaw. And the deli-style salads of marinated vegetables, pasta and sausage, tortellini and such were, for the most part, bogged down with gluey binders or overdoses of olive oil. Worse, a request for chicken and mushroom soup was met with a brown bowlful of what tasted like gravy, with lots of fleshy mushrooms but no sign of any chicken. Unfortunately, the best part of a meal here may well be the people-watching.

Take Me Home (downtown), 1921 Sunderland Place NW, 775-8396. Hours: 11 a.m. to 3 p.m. Monday through Friday. Prices: Sandwiches $2.25 to $4.50, salads $2 to $3. Cash only.

Hard as it is to believe, the ubiquitous tuna fish sandwich takes on new meaning when it's eaten outside -- say, in the quaint splendor of the garden court of the Columbia Historical Society -- and when it's prepared by, say, Take Me Home caterers, which operates a tiny carryout.

The menu of mostly sandwiches and salads is every bit a match for the setting, a grassy hideaway just a few steps removed from the downtown bustle. The hefty sandwiches -- sold by the half and served on thick slices of homemade bread, along with deep red tomatoes and crisp greens -- test the limit of one's jaws, but they are inventive and fresh-tasting creations. Don't miss the tuna fish, bolstered with the crunch of crisp green apples and livened with peppercorns and scallions.

The room-temperature empanadas, decorated with charmingly braided crusts, are equally delicious, stuffed with spicy ground Italian sausage. But my clear favorite was the earthy lentil salad, blended with bits of red pepper and feta cheese for a winning color and flavor combination. The only drawback here seems to be the absence of a trash receptacle, either in the carryout or the park.

Tom Sietsema is on the staff of The Washington Post Food section.