Lunchtime strollers, walkers and joggers who like a little culture with their noon-hour constitutionals will be pleased to learn that behind many a faceless downtown marble edifice exists a warm and bustling art scene.

To wit: a tour of building in the neighborhood of the State Department would currently reveal a Calder mobile, two Giacometti sculptures, several paintings by Dubuffet and a retrosoective of work by Washington artist Willem de Looper. A few blocks closer to the White House, there is a show of contemporary art from Tanzania, and back on Virginia Avenue at 23d Street, a small display of new talent.

Hosts are several quasi-governmental organizations like the Pan American Health Organization, the Federal Reserve, the International Monetary Fund and the National Academy of Science - Healthy, Wealthy and Wise, as they are sometimes calles.

Other downtown buildings also have regular exhibitions, of course, notably the Pan American Union, which now has a whole new Museum of Modern Art of Latin America attached to it. Additionally, several embassies, such as the Canadian (just opening a show of contemporary tapestries), the Australian and the Swiss mount occasional shows. The difference is that the mission of these organizations includes cultural proselytizing.

But why would Healthy, Wealthy and Wise which have nothing even marginally to do with art, get involved in the business of organizing exhibitions? Primarily for the enjoyment of their employes. "Why do we bother with lawns or flowers?" retorted a proud denizen of one such marble palace. "To make the palce more beautiful, more human and habitable, of course, and maybe even stimulate thought."

It is a notion that even the government has now made official in the new General Services Administration program called "Living Buildings." A new exhibition program has been initiated in that lobby (currently a salute to Black History Month, featuring two fine works by Washington sculptor Ed Love), as well as in Commerce Department building, where paintings by artists from the Association of Artist-Rum Galleries of Washington and New York's Organization of Independent Artists are on view adjacent to the auditorium. The space is up for grabs in the future.

Probably the oldest, and surely the best-established, exhibition program in this quasi art group is that of the International Monetary Fund, which has an inviting permanent gallery space just off the soaring, glass-covered atrium of its building at 700 19th St. NW.

The IMF program has the distinction of having grown out of the interest of the well-traveled staff that in 1962 founded an Art Society to which interested employes could belong for a modest sum, now $7.50 per year. The proceeds support gallery activities.

In recent months these exhibitions have ranged from a show of new work by Washington artist Alan Bridge to drawings and prints by Kaethe Kollwitz and a major survey of contemporary painting from the Phillippines.

The current show is typical of both the predominantly international flavor and high quality of IMF's program. "Indigenous Art from Tanzania" is in fact a show of art that would not have existed without an American Maryknoll nun, Sister Jean Pruitt. She went to Tanzania 10 years ago to start a workshop and introduced some traditional Makonde wood-carves to two-dimensional techniques, including batik, printmaking and painting on goatskin. Two years later an adjoining "house of arts" was opened it now supports four artists and 45 craftsmen.

This show concentrates on the work of four artists, most extraordinary among them, George Lilanga, an out of-work Makonde master-carver whom Sister Jean first hired as a watchman. She subsequently got him working again by introducing him to easily accessible two-dimensional media, and his batiks, drawings and calabash gourd carvings now teem with beautifully designed and highly expressive spirit figures that have all the power of Dubuffet. it is difficult to translate traditional skills into the modern vernacular, but Lilanga, the supreme artist, has made the transition effortlessly, maintaining the indigenous quality as well. It is safe to say that his work would be welcome in any museum of modern art in the world.

Augustino Malaba's batiks and woodcuts and Robino Ntila's etchings additionally make this show well worth the hassle of presenting oneself to the guard at the entrance of the building and asking permission to enter and see the art gallery, which is open during regular office hours.

Somewhat less frequent, though of high and often museum quality, are the exhibitions organized by the Federal Reserve, a modest reflection of the "Art-in-Banks" boom.

The Federal Reserve is unique in that it has a part-time professional curator, Mary Ann Goley, whose training in art history is reflected in several well-researched shows that have ranged in subject from "18th and 19th-Century English Painting" to "Francis William Edmonds," a relatively unknown 19th-century American banker who was also a fine genre painter.

Goley has also had the imagination to ask the Park Service for permission to install a large, three-part sculpture by contemporary American Ron Bladen in the grassy area adjoining the new Federal Reserve building. They were delighted, and thus the leaning Bladen piece, which can be seen from Virginia Avenue, is one of the very few minimal sculptures that can be seen outdoors in Washington.

Though currently deprived of regular marble wallspace in the old Federal Reserve building because of renovations, Goley has managed to mount a modest but revealing retrospective of paintings by Washington artist Willem de Looper on three floors of the Federal Reserve's eggcrate at 21st Street and Virginia Avenue. After entering via C Street, and asking permission of the guard under the Calder mobile, visitors can view the work, in chronological sequence, by getting on the elevator and stopping at the 2d, 3d and 4th floors, in that order.

In a real sense, the elevator ride is a metaphor for de Looper's progress, for it only after much able but very derivative work that he has climbed to a mature statement of his own in his current horizontal color formats. As a study in how even a good artist must struggle to find his way, the show is revealing. Those on a short lunch hour, however, might proceed directly to the fourth floor.

Because of space limitations, the largest, newest and best of the de Loopers in this show are on view across the street at the National Academy of Sciences, 2100 C St., which, with the help of David Schaff, organized this show jointly with the Federal Reserve.

The National Academy of Sciences has art throughtout the building, everything from scuplture by William Calfee to prints by Frank Stella and Red Grooms in the dining hall. Art-related films are sometimes shown in the auditorium during lunch hours.

The art exhibitions, however, are concentrated in the academy's posh, if rather dark, exhibition area, reached directly from the C Street entrance, where artists like Fred Eversley, Harry Bertola and Leon Berkowitz have been given shows in the past. "We want to make the point that the creative impulse that produces great science is the same impulse that produces great art," says Lucille Handler, whose husband is the academy's president, and who has managed to beg, borrow and occasionally to buy several dozen works of art to fill the academy's endless spaces.

The current show is a small borrowed sampler from the private collection of Dr. Milton D. Ratner, who has concentrated on three areas: African art, paintings by Jean Dubuffet and graphics and sculpture by Giacometti. Featured here are a bronze Giacometti called "The Nose," and provocatively juxtaposed with a handsome Yoruba carved head, another highly cubistic white marble "Tete" by Giacometti from 1934. A large gouache by Dubuffet, "Repas a Quatre," make this show a worthy destination for a lunchtime stroll.

Only one problem remains. Why is it that the academy, which helped launch the space age, still finds the problem of proper lighting insurmountable?

The Pan American Health Organization (PAHO) art gallery is different from all of the aforementioned chiefly in that it is run by a volunteer committee that seems to exercise little or no quality control over what is shown in its handsome rotunda-shaped gallery space.

The current show, "Six Woman Artists," is displayed in such dime-store basement style, that even if it was good art - which this isn't - it would look bad in this sloppy context.

Which raises an important point. Whatever the reasons for setting up art exhibitions, they will ultimately say something about the institution itself. Art implies a certain level of quality. Thus an institution must show art of a quality commensurate with its own work and standards. If it does not have the taste to do this, and do it right, it might better settle for potted palms.