On public and private buildings throughout Washington, Waldron Faulkner has, over the years, quietly left his genteel imprint.

His last work, before he retired, was the conversion of the Old Patent Office into two museums, the National Collection of Fine Arts and the National Portrait Gallery. The Portrait Gallery is celebrating its 10th anniversary with a variety of exhibitions, lectures and other special events.

One of Faulkner's first jobs, shortly after he settled in Washington in the late 1920s, was the restoration of the Blair-Lee House where presidents accomodate their foreign guests.

In between, in almost half century of busy practice, Faulkner designed, among others, the original campus of Madeira School, a number of other private school buildings, offices for the American Association for the Advancement of Science, the American Chemical Society, the Brookings Institution, five or six big hospitals and a number of private residences.

His most distinctive and charming building, I think, is his own house in Cleveland Park. Completed in 1937, it is among the city's first ventures into modern architecture. But - and this is characteristic of Faulkner's architecture - it is gently modern, a sublimated art deco.

The neighbors were a little apprehensive when they saw a steel cage go up on Faulkner's lot. But when the structure was enclosed with brick and stucco and decorated with subtle color (Faulkner wrote a book on color in architecture), they found the new house not only interesting but also likable.

Faulkner, now 80, is proud, and rightly so, of his house and the setting he has created for himself and his aristocratic wife, the former Elizabeth Coonley. She has been leading in innumerale civic causes. And architecture historians will tell you that she is the little girl in a famous photograph of one of Frank Lloyd Wright's best houses, the Coonley House, in Riverside, Ill.

Waldron Faulkner, looking young for his age with a full shock of snowy hair and a calm alertness in his voice, is as immaculately dressed as his buildings. Over tea and lettuce sandwiches he and Mrs. Faulkner readily accede to reminisce.

He was born in Paris, the son of a Connecticut Yankee painter who moved in the circle and genre of John Singer Sargent and Frank Millet and who also had an apartment in Venice, where the family spent the summer.

Waldron Faulkner first studied engineering, but was soon attracted by architecture and Yale. It was the time when beaux arts began to yield, or, rather, dissolve into art deco.

Faulkner started to practice in New York but there were no jobs. He moved to Washington in 1926 because, what with all its government workers, this city was hardly touched by the Depression. There was quite a bit of building going on.

"Washington was a sleepy Southern city in those days," Faulkner said. "You were out in open country in a few minutes.

"It was a Southern city in attitude, too. I remember I wanted to hire a black draftsman, a Howard graduate. But one of my clients, the Alcoa corporation, did not permit me to let him work on its job." Faulkner became the first president of the Washington Urban League, a civil-rights organization.

Modern architecture, he said, did not arrive in Washington with a bang, as a challenge or menace, as it did in most other cities.

"Well all considered modern architecture an ideal," Faulkner said of the small group of Washington architects before World II. "But we did not really know what it was."

So Washington never had any radically modern buildings in the Bauhaus and LeCorbusier manner. When a national competition for a Smithsonian Gallery on the site of the present Air and Space Museum came up with one - a handsome Bauhaus style building by father and son Eliel and Eero Saarinen - it was simply ignored. Until Eero Saarinen built the Dulles Airport terminal and Miles van der Rohe built the Martin Luther King Library, the only clearly modern building in town was William Lescaze's Longfellow office building at Rhode Island and Connecticut Aves. built in 1940.

The bulk of the city's new buildings was modern with a small "m" - a little ambiguous about their style.

Critics often called the Washington architecture of the 1940, '50s and '60s "mediocre." Some of them are. But the majority, as Francis D. Lethbridge has pointed out, are of a higher architectural quality than buildings of the period in other cities.

If they were not assertively Modern, it was because Washington architects like Waldron Faulkner did not want them to be. They wanted them first and foremost to fit harmoniously into the evolving and basically classic and conservative cityscape.

"Dad was never defiantly original," said Avery Faulkner about his father "but he applied great originality to make his building pleasing and in good taste."

The restoration of the Old Patent Office, built 1836-1867, which Philip Johnson has called "the greatest building in the world," was Waldron Faulkner's most difficult job. It was the first genuine antique the General Services Administration undertook to restore and adapt to new use. And GSA in those days was adamant and rigid about its inexperience so as not, to say indifference about old buildings. Faulkner had to serve two masters, the GSA and the Smithsonian.

In the end, however, the restoration won several architecture awards and National Portrait Gallery director Mavin Sadik praises faulkner for "his sensitive reverence for the authentic and original character of the Old Patent Office."