Washington lost a lot when architect John Wiebenson died in a tragic accident two weeks ago. "Wieb," as he was widely known, was a man of strong beliefs and many accomplishments.

He was, for instance, the city's most persistent and effective architectural gadfly. He came to town from California 36 years ago, set up house near Dupont Circle and right away started to criticize the way things were.

There was, of course, no lack for big, fat targets. Plans were underway to cut a mile-long, 50-foot-wide swath on the north side of Pennsylvania Avenue to make it a grander, more imperial parade route. A vast patch of Southwest Washington had just been bulldozed and redeveloped in the name of urban renewal. Smaller-scale outrages loomed all about.

Wiebenson rejoiced in the attack. But he didn't just attack. "It's one thing to be critical, and quite another to come up with counterproposals and real illustrations of both the problems and the alternatives," notes architect Mark McInturff, a former colleague in Wiebenson's architecture firm.

That is precisely what Wiebenson did -- he was sort of a systematic nudger, appearing at public meetings, writing and illustrating articles and even, on occasion, turning the talents of his students at the University of Maryland towards the "solution" of this or that nettlesome Washington problem.

Forget that superwide sidewalk and save the old buildings along Pennsylvania Avenue, Wiebenson would insist in persuasive words, and then clinch the argument with hand-drawn pictures showing how his idea would produce a livelier, more humane alternative. Unquestionably, this advocacy helped create the climate for the much-improved avenue plan that emerged in the mid-1970s.

"Redevelop redevelopment" was the Wiebenson motto in his assaults on large-scale renewal plans such as the one for Southwest. And though his incisive proposals to improve that plan did not have much effect, they still can be profitably revisited, for the problems remain. For example, in a 1977 article in The Washington Post, Wiebenson showed how the barren 10th Street SW promenade might be enlivened with stores and other attractions -- not a bad idea in 2003.

Wiebenson also was one of the city's earliest preservationists, an advocate for the old whose tirelessness and creativity had much to do with the saving of the Old Post Office Building and Willard Hotel, among other distinguished buildings once slated for demolition. A key participant in the founding of Don't Tear It Down, the organization that morphed into the D.C. Preservation League, Wiebenson passionately believed that the scale, texture and personality of old buildings contribute greatly to the life of the street.

Not surprisingly, Wiebenson was a man who practiced what he preached -- lively streets were important in both his personal and professional lives. His 6-2 frame and distinctive gait were familiar sights on the streets of his Dupont Circle neighborhood for the better part of four decades. He and his wife, Abigail, reared three sons in the S Street NW house that friends say Wiebenson always seemed to be reworking.

A talented designer, Wiebenson displayed a consistent interest in fresh, light-filled open spaces, frankly expressed structural supports and touchable textures such as the wooden beams and walls of his own residence. With its exposed steel columns and pediments and its California-style second-story balcony, the little commercial project he designed at 1629 Connecticut Ave. NW is an airy, vivid punctuation mark among the avenue's masonry facades. "I'd like to sit there and have a cup of coffee and watch the trees wave in the wind," Wiebenson once told an interviewer. "I think it's that kind of place."

Both as an architect and a person, Wiebenson remained a fierce but caring individualist. At a memorial meeting last weekend, Dupont Circle neighbors and civic activists testified that the architect could be counted on for assistance in little matters -- a neighbor's broken stair, say -- or big ones, such as a fight to prevent the construction of yet another out-of-scale atrocity.

This civic-mindedness extended to the way Wiebenson practiced architecture, for he believed in architecture with a social purpose. His first big Washington job back in 1968 was to head a team designing temporary housing for Resurrection City on the Mall, the last stop on the national Poor People's Campaign organized by the Rev. Martin Luther King Jr.

Wiebenson's firm, located for decades in walkup rooms on Connecticut Avenue just a couple of blocks from the family home, always did more than its share of pro bono work for nonprofit organizations. Much more. It is eerily fitting that he died in a freak accident on a Sunday visit to a job the firm was doing for Martha's Table, a youth-oriented agency on 14th Street NW.

The 70-year-old, Colorado-born architect had been doing design work there for nearly 20 years, taking on the remodeling and expansion of building after building as the organization grew. Wiebenson's attention to detail was extraordinary. Martha's Table president Veronica Parker once said it this way: "You need somebody like Wieb who'll ride his bike over here and deal with the problem very quickly."

Almost immediately after Wiebenson's death, the Washington Architectural Foundation decided to give an annual honor for architecture in the public interest, to be called the John "Wieb" Wiebenson Award. Mary Fitch, executive director of the D.C. Chapter of the American Institute of Architects, says the first recipient will be Wiebenson himself.

That is one sort of tribute, richly deserved. But other, more personal tributes catch the flavor of the man. "Whenever I met him I got kind of a smile inside," said longtime friend and fellow architect Robert Schwartz. "He was a very, very honest person and wonderfully wacky -- he just made you happy that he was just being Wieb."

Or, as his architectural partner Kendall Dorman put it, "I just loved coming to work and seeing the guy."

The late John Wiebenson was one of the city's first preservationists, helping to save such treasured structures as the Old Post Office Building, shown below in 1976.