Open Mondays through Fridays for breakfast until 10:30 a.m. and lunch from 11 a.m. to 3:30 p.m., Saturdays and Sundays from noon to 4:30 p.m. Street parking on weekends, but during the week, best bet is the Gallery Place subway stop. Accessible by wheelchair. No credit cards; no reservations.

From lowly beginning - namely the subway station at McPherson Square - our family joy-rode the region's mighty Metrorail the other day and topped off our tour with a lunch stop at a first-rate downtown eatery that made the whole jaunt track together smoothly.

Somewhere I read a study indicating that children seemed more adept than adults at handling Metro's farecard machinery. Maybe it's because kids read the directions, but anyway our son, 10, and daughter, 8, breezed through this process for us.

There are many ways to play the subway game, but here's how we hit the lowlights for 40 cents apiece before lunching at a cafeteria called the Patent Pending:

From McPherson Square we rolled past Foggy Bottom, under the Potomac, past Rosslyn, above ground through Arlington Cemetery and up the ramp overlooking National Airport.

Then, without leaving the station, we rode back to Rosslyn, went up and sdon that incredible escalator (again without exiting) and went on to Metro Center for a switch to the line that takes you one more stop to Gallery Place - where we lunched at the Patent Pending Cafeteria inside the National Portrait Gallery at 8th and F Streets NW.

Through the gallery's main door, down the corridor to the right and then left, we found a sparkling little room full of tables with metal caned chairs, pleasant prints on the walls and a counter of fresh fruits, breads, pastries and a grand variety of sandwiches and other cleverly named things to eat.

After testing Metro's blue line and red line, our beeline to this cafeteria produce no line - only an affable staff ready to whip up individual orders.

The imaginative specials included the "Soup and a Half," a half-sandwich of pastrami on pumpernickel with a bowl of gazpacho for $2; the "Tippecanoe and Tuna Too," a tomato half topped with tuna salad and served with a slice of canteloupe for $1.95: and the "Fruitgurt" "all natural" yogurt with pineaple chunks and apricot for 95 cents.

The Patent Pending's sandwich specials, each made to order garnished with red onion, lettuce, tomato, green pepper, Russian dressing and a slice of pickle are: The Priscilla Mullin (turkey and Swiss cheese) at $2.50; the Fanny Brice (roast beef) at $2.45; the Walt Whitman (turkey salad) at $2.05, and the Honest Abe (turkey, roast beef and Swiss cheese) at $2.95

My wife reported that the "Courtyard Salad" at $1.55 was a fresh and tasty gathering of tomatoes, lettuce, mushrooms, cucumbers and a yogurt-type Russian dressing. Our son was unusually effusive about his Bulldog, a hot dog with homemade chili for $1.15. (Other dogs, by the way, come with various bites to them, for 95 cents, or with sauerkraut, for $1.15.)

Our daughter observed pertinently that her egg salad sandwich at $1.25 - was not the packaged flat kind that you usually find in cafeterias. I should say the same for my roast beef on rye at $1.85, for it was well rounded with rare meat.

There were some good-looking bagels' about, too, but somehow our crowd wound up with three little bags of chips. Our drinks were soft, though beer and wine are availabe.

For dessert, there was apple pan dowdy at 85 cents, cheesecake at 95 cents, whipped cream cakes at 95 cents, fresh fruits, including watermelon, at 25 cents, or canteloupe at 40 cents.

Our son chose a piece of cake that turned out to have a thin side to it, which the staff noted by voluntarily knocking the 95-cent price down to 50.

For under $2 each, there's an even longer list of soups, salads and sandwiches for the adventuresome. What's more, all these treats can be trotted outdoors to tables in the attractive gallery courtyard - which more than a few-downtowners seem to enjoy.

Our total bill for this fine fuel stop on our subway safari was $8.74 - hard to match for quality and atmosphere.