For reasons that defy logic, economics and social fashion, the little red brick house and its denizens endure here, on one of Washington’s least lovely downtown office blocks, like a bloom in a crack of the concrete canyon where I Street merges with Pennsylvania Avenue NW.

The green wood door is topped with an antique fan of leaded glass and adorned with a brass knocker worn smooth from use. Knock, and be admitted.

A throng of maybe 100 is sipping wine and nibbling chicken liver pate and skewered sea scallops. Most are dressed in black tie or evening gowns. Some of the dinner jackets are adorned with medals, indicating that the wearer is a military man. Many are spiced with colorful vests or adventurous cummerbunds, suggesting a free spirit. One of the freest spirits is art professor Edward “Eddie” Purcell III, who has cast aside all thought of a tux in favor of a full-length red silk 1950s vintage Chinese smoking robe.

Almost anything goes at the Arts Club of Washington, whose clubhouse is the quarters where James Monroe lived for a few months as president, in 1817, while the White House was being rebuilt following the British barbecue of 1814.

“The thing about the Arts Club, either you get it or you don’t,” says Robert Sacheli, club program chairman. “We have a lot of eccentric people here. We’re very proud of that. We encourage eccentricity.”

The bohemian side of the Social Register started calling this house home in 1916. Some of the same upper-crusty social folkways continue to be pursued, along with an artistic mission that seems equal parts anachronistic and vital. At a time when arts funding is being cut everywhere else, and private galleries are closing or moving to other parts of town, the Arts Club’s nearly $1 million annual budget is stable. The money goes to arts-related programming, historic preservation and club activities. The club hosts monthly openings for four artists in its four exhibit spaces, presents weekly free music concerts and sponsors scholarships and literary prizes. The public is welcome six days a week.

It must be the only club in this still-clubby town that is for members only — and for everybody else. This paradox is the beginning of a long list of reasons why the Arts Club makes no sense — and therefore why it survives. It is at once whimsically un-Washington and profoundly old Washington.

“There’s a comfortable dowagerism to it,” says Lars Etzkorn, a lobbyist. “Folk who’ve been here a long time, even if during the day they might work at the Defense Department or someplace quintessentially political D.C., they have a creative side that they want to express, that they enjoy expressing. And this allows them, if you will, to come out of the closet.”

Look around and listen. The sensory overload takes a minute to get used to. It is multimedia, decidedly analogue, definitely unplugged.

Club president Jack Hannula, a painter, steps onto a little stage and recites a poem he wrote for this recent black-tie occasion, the annual Monroe Dinner:

Approach we our centennial

With march of time perennial

Hotel next door and there, a pub

Where palms are greased and elbows rub

’Tis Washington, our country’s hub

Though Monroe’s house is now our Club.

Purcell has the happy duty of announcing that, from a field of 86 contenders, Wheaton College art historian R. Tripp Evans has won the club’s annual $10,000 Marfield Prize for national excellence in arts writing for lay readers, for his groundbreaking biography “Grant Wood: A Life.”

Now pianist Stephen Brown settles before one of the club’s two 80-plus-year-old Steinways, and soprano Marje Palmieri sings a selection of bel canto solos from the late 18th and early 19th centuries.

Sated with wine, poetry, prose, painting and music, the members and guests step out to the garden for a meal of sweet pea soup, pork tenderloin, crab cakes and lemon short cake, cooked by club chef Bill Colliton and served on white-and-gold Monroe china.

Because it is raining, the garden has been tented. And because everything at the Arts Club has a homemade, handmade, all-in-the-family feel to it, one side of the tent is leaking on the ladies and gentlemen. A waiter with a big broom is heroically diking and rechanneling the floodwaters swirling around the dainty slip-on opera shoes.

Taking note of such exclusive precincts as the Metropolitan, the Cosmos, the Washington and the University, the artists of the nation’s capital wanted a club of their own.

The founders had national reputations but were not aesthetic rebels bent on upsetting the establishment. They were the establishment. They rented the Monroe house in 1916, then purchased it with proceeds from an art auction held at the Willard Hotel. Dues were $15 for artists, $20 for non-artists.

In a radical departure from social norms of the era, women were welcomed as equal members. Club records do not indicate whether the artists were as broad-minded when it came to race. The first black club president, Joseph Cabaniss, was elected in 1994.

Quickly, the club attracted 500 members and was “an important factor in the artistic and social life of Washington,” the journal Art & Archaeology noted in 1919. Arty socialites including D.W. Griffith, Claudette Colbert, F. Scott Fitzgerald and Tallulah Bankhead partied there.

The annual costume Bal Boheme was a highlight of the social season. In 1934, first lady Eleanor Roosevelt was the honorary patroness of the ball.

As years passed, arts venues multiplied, and so did definitions of what is art. The club was crowded out of the artistic spotlight. Club membership was less appealing to new generations with disposable income for dues, now $750 a year.

Yet the Arts Club refused to die.

In the late 1980s, former club president Walter Burns, a real estate broker, executed a brilliant plan: He directed the club to lease its “air rights” to a developer erecting an office building on a nearby corner. The club’s commitment to stay small allowed the developer to build bigger — a privilege for which the developer was willing to pay handsomely. Escalating over a 99-year lease, the annual stipend now stands at $165,000 — a fat subsidy that most arts organizations can’t count on.

The club reaps about $500,000 from renting the space and Colliton’s cooking for special events. Washingtonian Bride & Groom magazine just named it among the top venues for a wedding reception. As a cushion, the club also has an endowment of nearly $2.7 million from wealthy benefactors of yore.

So here are the house, the art, the food, the wine. What about the guests?

“One of the nicest things about this place is, it’s under the radar,” says program chairman Sacheli, publication manager for VSA, the international disability arts organization. “One of the drawbacks is, it’s under the radar!”

The morning sun splashes in the windows of the third-floor studio, where president Hannula brushes sap green and ultramarine blue highlights onto a New York street scene.

Downstairs, members of the Maryland Opera Studio are rehearsing in German for their free public noontime concert, to be followed by a members luncheon. New work by four more artists has been hung in all the galleries. There will be a public opening with free wine and artist chats in the evening.

“It’s the sort of place you don’t normally find in Washington, where it’s all zoom-zoom, how do you advance your career, how do you leverage relationships for the betterment of your client,” says Etzkorn, who lobbys for the National League of Cities. “At the Arts Club, nobody ever asks what it is that you do.”

If you do ask, you might be surprised. The 2008 obituary of Norman Longfellow Smith noted that he was a former deputy chief of operations in the CIA’s counterintelligence service — and treasurer of the Arts Club.

“For me, it became a nice sanctuary away from the normal din of Washington,” says Henry Sienkiewicz, chief information officer for the Defense Information Systems Agency.

“There are several relatively strict rules, all unwritten, one of which is: No politics,” says Skip Keats, a Web designer. He adds, “It’s a place I can wear slightly outlandish attire, and no one will blink.”

Of course, what Keats means by slightly outlandish is, say, white tie before 8 p.m. Or a dinner jacket with a bit of paisley to it and a red lining, accessorized with “slightly purply-red” formal shoes.

Which only underscores how at the Arts Club, whimsy and nonconformity are nurtured within the context of an equally cultivated appreciation for tradition and old-world culture.

“They’ve got place cards! I love black tie!” says Jane Work, a retired communications executive who moved down from the New York area. “It’s the first time I found any people like the people in Greenwich Village.”

Black tie? Greenwich Village?

“This kind of grand townhouse really ends up being your place,” continues Work, who chairs the club’s scholarship program. “The people are interested in the arts. They’re non-judgmental. The food is excellent. The wine is good.”

“And free-flowing,” says Purcell, who has joined Work in the club library.

“And free-flowing,” Work says. “I’m not the shy, retiring type.”

“There is no shortage of characters here,” says Purcell, who attended another recent club dinner — an evening of Shakespeare, song and $3,450 awarded in poetry prizes to college students — attired in a long, blue silk, 100-year-old Manchu Chinese court jacket.

Hardly anyone gets turned down for membership. Some say it has not happened in recent memory. Others recall an occasion when an applicant was deemed too unpleasant to be good dinner-table company.

“People are more interested in clever, fun people,” Purcell says.

Membership drifted down toward 200 but has bounced back slightly. The club still has a serious demographic problem. Of the 230 members listed in the directory, just four are counted as junior members, or younger than 35. A recent club survey found that 40 percent of members do not use the Internet.

Nevertheless, this month the club launched a new Web site. The more tech-savvy members talk among themselves on the 17-month-old Facebook page.

An Arts Club Twitter feed is coming soon.

The wrong question to ask about a place like the Arts Club is the one anybody would want to ask first: So, is the art any good?

If you insist on knowing: Yes, some of it is quite good, according to independent experts affiliated with institutions such as the National Gallery of Art, the Corcoran Gallery Art and the Kreeger Museum, whom the club enlists as volunteer curators.

Three of the four artists featured each month are nonmembers who tend to be interesting and accomplished but not necessarily prominent. Same with the musicians in the club concerts.

The work will tend not to blow your mind or offend your sensibilities. A crucifix submerged in urine will never be presented at the Arts Club, nor a chamber piece that includes four minutes of silence and the quacking of a duck. But much of this art will quicken your aesthetic pulse and might look good in your living room. (It generally ranges in price from $500 to $5,000.) You might return to your cubicle after lunch with Beethoven’s Piano Sonata No. 7 in D in your head.

“It has a purpose,” says poet E. Ethelbert Miller, one of the outside judges for this year’s arts writing prize. Past judges have included Joyce Carol Oates and Jamaica Kincaid. “Everybody is not going to go to U Street. Everybody is not going to go the Folger Shakespeare Library.”

The Arts Club is a quiet hymn to the idea that art is not remote, that art can be made a part of daily life. The club is a safe space to converse artfully, entertain artfully, dress artfully, host artfully, program artfully and make art artfully.

So let us sip the free-flowing wine at another four-artist opening on the first Friday of the month. Let us join the more than 100 attendees wandering through galleries on three floors, contemplating dozens of new paintings, etchings, woodcuts and sculptures.

“My goal is simple but not easily attained,” says Joan Root, one of the featured artists. “To create an image that will bring the viewer a sense of refreshing astonishment, by seeing something familiar which also appears to be, somehow, newly seen.”

Her hyper-real and crisp portraits of vegetables profiled against sweeping landscapes are one way she attempts that.

Are the paintings the art? Is the house the art? The polished antiques? The two fabulous pianos? Are the people the art?

Let us mark in our calendar the upcoming “Birthday Salute to Walt Whitman,” May 25, open to the public. It will feature a soprano, a contralto and a pianist performing works inspired by the poet.

And then as the crowd thins out, let us do the same and shut the clubhouse door behind us.