Marvin Nathan is 75. Edgar Stone is 84 — “I’ll be 85 if all goes well.”

The pair engage in an effortlessly witty, acidly self-depreciating give-and-take honed to perfection throughout their four decades of friendship. When the two share a laugh — and this happens a lot — they resemble nothing so much as Statler and Waldorf, the two elderly gentlemen who sat in the balcony and heckled “The Muppet Show.”

You could say Nathan and Stone are the elder statesmen of the Concordia-Argonaut Club. But you’d be wrong.

While Stone jokes that he’s been a member since the days of the pharoahs, there are more than a few older men — and since the 1970s, women — hanging around at the venerable city club. And they’re not just drinking and playing cards (but there’s plenty of that); they’re lifting weights, playing handball or basketball, swimming or, naturally, shvitzing in the steam room.

Now celebrating its 140th year of existence since being founded by San Francisco’s German Jewish patricians — who couldn’t get a membership elsewhere — the Concordia-Argonaut is vestige of an age that has passed. While it’s still possible to visualize the Strauses and Fleishhackers playing cards, smoking stogies and downing shots of single-malt scotch while strolling through the club’s magnificent and ornate rooms, that era is a rapidly receding memory.

Instead, over the past 15 years, the club on Van Ness Avenue has been attempting to morph into a “family club,” according to attorney Lou Haas, 64-year-old president of the board.

“My kids were raised here. I brought my two boys here from the time they were 2 years old and 6 years old,” he says.

The club has become part of Haas’ daily ritual. Every morning he’s there at the crack of dawn for a basketball game, a few reps in the weight room, a schvitz, a shave and he’s to work by 9:30.

But more and more men and women in his position hoist their early morning weights at a gym featuring a treasure trove of lifting equipment resembling the Marquis de Sade’s summer collection and loud music thumping through the sound system.

Haas has been there, too, and he compares them to “warehouses” or a “physical plant.” With the Concordia’s monthly dues ranging from $75 to $250 depending upon one’s age, he added, the cost is roughly comparable.

But, more importantly, how good is the buffet at 24 Hour Fitness or Club One? You don’t get a meal at those gyms, you get a Power Bar, Haas notes with a chuckle. But the Concordia-Argonaut’s buffet is “legendary,” he says. And reasonably priced, to boot. (In addition to the sliding-scale dues and a one-time initiation fee, however, club members are required to spend $800 on food or drinks per year.)

Top-notch noshes is one of the reasons Stone, a member since age 8, keeps coming back. The other?

“Inertia!” he says, cracking up both Nathan and himself.

In Stone’s 77 years of membership — and Nathan’s scant 40 — the two have witnessed and contributed to the evolution of the club into what it is today. And don’t say they never sacrificed. When women joined, men had to start wearing trunks in the swimming pool, deadpanned Nathan. Now that was a big deal.

Haas, who doubles as board president of j., proudly notes that the Concordia was the first among city clubs to admit women, which it did in the early 1970s. It was a gallant move, but not entirely spurred by gallantry. Then-Supervisor Dianne Feinstein’s all-female party had been refused service when her husband, a member, was late showing up for a lunch date. She was not amused, and there were even subsequent rumors bandied about of the club potentially losing its liquor license.

That (in addition to modernizing attitudes) helped get women through the door.

Opposition to wearing swim trunks (or having women around to disrupt card games and stogies) was actually quite a serious barrier to overcome, as quaint as that might seem.

“All these old goats wanted to go swimming with no trunks, if you can imagine anything more ridiculous. But that’s how it was,” sighs Annette Dobbs, one of the first female members of the club and a former president of the S.F.-based Jewish Community Federation.

While Dobbs says she “can’t complain” about goings-on at the club over the past three decades, in the days before women were admitted, life was different.

“I can tell you, when [former Fairmont Hotel owner] Mel Swig was still around, he called a meeting at the Concordia Club, and I was on his committee. And when I walked in, all the men looked at me like they were going to have a heart attack,” she recalls.

When members and employees informed Swig that women were not allowed in the club, “he said, ‘I guess I’ll have to take my business elsewhere.'”

A compromise was reached in which the committee met, cloistered, in a second-floor room, and the members were spared having to gaze upon Dobbs’ feminine visage.

Nathan and Stone bemoan the fact the club hasn’t attracted more female members, but, since prospective members must be invited by a current member, sponsored by two more and then subsequently voted in (or not), it’s no surprise women and minorities have filtered in slowly. Thirty years after opening its doors to women, 85 percent of the Concordia-Argonaut’s 300- to 400-person membership is still male, and virtually everybody is still white and Jewish.

Think of the Concordia-Argonaut as the world’s largest Faberge Egg. On the outside, to paraphrase Dom DeLuise in “History of the World,” it’s “nice, nice, not thrilling but nice.” It’s a box-shaped building the color of morning fog, whose only external conceit to dandyism is an ornately trimmed awning. To hundreds of pedestrians a day, it’s just a nondescript edifice between Mel’s Diner and a Peruvian joint. The No. 47 bus rumbles by every

15 minutes; the Concordia is just another building reflected in its grimy windows.

But the interior of the club is every bit as jaw-dropping as its exterior is ubiquitous. The Concordia-Argonaut’s building is a century old, and it shows. Not in its wear and tear (Nathan worked to fix up decrepit décor during his club presidency decades ago) but in its expansive and ornate layout.

Walking through a college campus or government capital, it’s easy to figure out which structures were erected in the first half of the century or before and what got slapped together post-1950. It’s as simple as highlighting the differences between the Kremlin or a “Stalin’s Wedding Cake” apartment tower.

The Concordia’s halls are wide and welcoming, and decorated with rich, wall-to-wall carpeting and wood interior trim. The walls are coated with artwork, often depicting subjects such as fox hunts or endeavors of a similarly aristocratic (and exotic) mien.

The leather chairs and polished tables befitting a turn-of-the-century British explorer’s club — they’re all here. A number of the elegant rooms really do appear as if they should be sets in which actors portraying Jack, Bobby and Bob McNamara argue about the future of mankind in a Cuban Missile Crisis docudrama.

Upstairs, the dining room is vast and impeccable, and the buffet dispenses mountains of steaming, delectable food (including shrimp — the club is as kosher as a cheeseburger). On many early afternoons, just four or five elderly gentlemen fill out the cavernous room, scarcely making a dent in Mt. Crustacean.

The Concordia’s basketball court looks as if it was drawn up by Bernard Maybeck, or, perhaps, Sea Ranch designer Lawrence Halprin. (It’s actual designer? Gustave Albert Lansburgh.) Rustic wood paneling gives way to an impossibly high ceiling and a skylight permeated by ethereal rays of sun. Players never looked so elegant chucking air balls as they do here.

The downstairs pool, hemmed in by wall-to-wall marble, is similarly grand. Backstrokers are treated to a ceiling painted to resemble the soft blue sky and cottony wisps of cloud appearing during the one or two perfect San Francisco afternoons a year.

In its heyday, the club carried a 625-member limit and a lengthy waiting list. Nowadays, there’s ceryainly no waiting list.

Nathan and Stone sit beneath a massive Japanese decorative partition — older than the two of them combined — in the club’s grand lounge, and discuss and debate the past and present of the Concordia-Argonaut.

Stone has nothing but fond memories of his youthful days at the club (his membership actually predates the 1939 merger with the struggling Argonaut Club, which drew Germans and Jews).

At the time of the amalgamation, club events were so well attended that coaches were hired for youth sports. Occasionally a Jewish boxer or ballplayer came through; Stone still has an autograph from Jackie Fields, the onetime middleweight champ of California.

But times have changed.

“When we came back from the war, everyone was worried about making a living and getting active in business and so on,” says Stone.

Adds Nathan, “I don’t know what will attract families back to San Francisco.”

Not that the club hasn’t battled back from hard times before.

A 1981 kitchen fire gutted the structure. Nathan, the president at the time, wryly notes that after the fire, inspectors discovered serious structural problems that could have resulted in a catastrophic collapse (specifically, the kitchen could have, literally, gone to the bathroom, which was one floor below). With an expensive reconstruction looming, membership halved.

Yet, by 1982, membership returned to its customary 625.

After the 1989 earthquake damaged the structure, membership again dwindled to half-full, as Haas and Claude Rosenberg passed the hat to raise nearly $7 million for repairs.

But this time, people haven’t come back.

With the exodus of families to the suburbs, the crippling price of private schools, changing family structures and the ascension of television as the pastime of choice, Stone is uncertain of the future of Concordia-Argonaut, or, indeed, any city club.

Nathan, however, expressed optimism — to which Stone laughs and shouts, “good!”

“We have such an enormous amount of opportunities to offer for leisure activities, meeting activities and camaraderie among club members, so I’m extremely optimistic,” Nathan says.

Dobbs, still a dynamo at 83, says as long as the club keeps its doors open, people will keep going in. But it won’t be the same club in which her late husband, Harold, played cards and hung out.

“With two-salaried families where the wife and the husband work during the week, the younger women I know are not about to say, ‘Go have a good time on Wednesday night, Saturday and Sunday.’ They’d say, ‘What are we going to do?’ At least

I would, that’s for damn sure,” she says with a chuckle.

City clubs may hearken back to a day and age when men wore hats out of doors (but, come to think of it, Haas still wears a hat out of doors). Not surprisingly, he’s optimistic about the club’s future, though it’s not an optimism born from mere nostalgia or a sense of duty.

In a fitting analogy, he’s predicting the club may get a transfusion.

With the California Pacific Medical Center moving into the former Cathedral Hill Hotel a stone’s throw from the club’s awning, a number of doctors and nurses might opt to make the Concordia-Argonaut their headquarters for a quick workout and bite to eat. And you better believe Haas is eager to see a few hundred doctors, nurses and administrators plunked down into a neighborhood where most people wouldn’t go unless they had a specific goal in mind; say, a pressing need to purchase a bowl of buffalo chili at Tommy’s Joynt or a Bentley at the dealership.

“It’s a home away from home,” says Haas.

The club has become part of him, and he has become part of it.

“I used to think, ‘Gee, what about those old guys?’ Now I am one of the old guys.”