Charles Eames, the better-known half of the 20th century's best-known design team, always preferred to call himself an architect, despite the fact that he and wife Ray Eames--the other half of the team--designed only one notable building.

Most conspicuously, Charles and Ray Eames designed chairs--more than 50 of their beautiful, practical designs remain in production. Some of the designs date back half a century, but the chairs, at once rational and romantic, retain their allure.

The Eameses made dozens of bright, cogent, innovative films for mighty corporations, and also just for the heck of it. Their multilayered designs for exhibitions forever changed the way exhibitions are designed. The toys they conceived for fun and profit epitomized both sophistication and childlike joy.

In a way, it would seem that in a busy, decades-long collaboration the couple did everything but architecture. Yet a visit to "The Work of Charles and Ray Eames: A Legacy of Invention," the hit summer exhibition at the Library of Congress, proves that Charles was more right than wrong to insist on his professional identity as an architect.

Simply put, there is an awful lot of architecture in everything the Eameses did. Charles was trained as an architect, and the training had a lasting effect, even though his credentials at the time he met Ray in 1940 were modest at best. (With a succession of partners, he had managed during the Depression to design and build several private homes in the Midwest, only one of which was even faintly predictive of the long-lasting creative explosion that followed the Eameses' move to California in 1941.)

This fundamental interest in architecture shows through in the structural sophistication--and playfulness--in the objects the Eameses designed and produced. This is particularly evident in the chairs, of course, but you can see it everywhere.

For example, the House of Cards--that wonderful 1952 toy made of large, slotted, interlocking rectangles of cardboard, each with a different colorful image on both sides--is perhaps the ultimate Eames object. Ingenious, attractive and interactive, it appeals to the child in all of us--and it stands up.

Achieving stability is of course the ultimate aim of most structures. But in bridges, buildings, chairs and toys alike the most fascinating part of the enterprise--and the source of considerable aesthetic satisfaction--resides in the answers to the question of how a given structure achieves the goal.

The Eameses and their workshop in Venice, Calif., excelled in this aspect of the game. The studio became famous for the prodigious amount of work that went into a given project--voluminous research followed by trial and error. Materials such as laminated plywood or metal or fiberglass were exploited for their inherent structural and expressive capacities, and combined in surprising ways.

Consequently, seeing the way things stand up and the way the pieces fit together is part of the joy we derive from looking at or sitting in a given Eames chair. First we experience the whole--the curvy wire frame of the Bikini Chair (so titled because its synthetic upholstery covers only part of the form). Then we begin to investigate the all-important details--the simple bolts, the splayed skeletal legs made of wood and wire, the metal-plate swivel.

The chair and its parts seem so unpretentious and elegant--signs of the Eameses and their studio at their very best. The days and weeks of thought and labor almost disappear behind the authoritative finished product.

Indeed, much of the fascination of this show lies in the revelations of the amount and kinds of work that actually were necessary to make things that seem so straightforward. Being able to examine original panels and other documents for the Eameses' still-captivating short film "The Power of Ten," an exploration of the known universe from its biggest to its smallest elements, is a museological equivalent of pulling back the curtain on the Wizard of Oz.

Simplicity, appropriateness, economy, delight--qualities we learn to expect in Eames-designed things. The "best" list most definitely includes the couple's sole architectural triumph--the house on the Pacific Palisades in Los Angeles that they designed in 1949 and lived in for the rest of their lives. (Charles died in 1978, Ray in 1988.)

With its structural system of lightweight, prefabricated steel posts and beams, and its Mondrian-like walls made of colored panels and translucent or transparent glass, the house still stands as an icon of America's post-World War II optimism. It was inexpensive and forward-looking, very much a positive expression of its own time--but the true mark of its quality is that half a century later it still looks like a fresh idea.

The exhibition contains a scale model; photocopies of original plans and drawings showing the final version and a less arresting first try; sketches; still photographs; and two videos--a recent effort by Charles' grandson (and filmmaker) Eames Demetrios that takes you on a four-minute tour; and a 10-minute slide show put together by Charles and Ray. All of this information gives a visitor the chance to become genuinely familiar with a little 20th-century masterpiece--quite a privilege.

The Eameses never precisely defined their individual roles in the design. Charles undoubtedly did the basic structural drawings; Ray, who was an accomplished abstract painter when they met, is known to have worked on the patterns of the walls. Beyond that, distinctions are impossible, but it is clear that Ray's contributions were as important as those of Charles.

There is a liberating charm about the Eames house that comes from different, even conflicting sources. It is a proud man-made object that stands in harmony with, but distinct from, nature. It is a cheap prefab structure that honors age-old standards of craftsmanship. It is a stripped-down modernist statement that, contrary to expectations, vibrates with signs of life.

Architect Robert Venturi honored the Eameses for having "reintroduced good Victorian clutter." With its abundance of colors, textures, images and artifacts assembled for intrinsic, individual qualities, the house was like an exercise room for two pairs of extremely educated eyes.

The Eames house is modern architecture with an intensely human touch. The sharpness of the couple's vision liberated them to throw away the rule book that said modern buildings had to be antiseptically "pure"--a lesson that needs relearning every once in a while. There is no better time or place to do so than this summer at the Library of Congress.

"The Work of Charles and Ray Eames: A Legacy of Invention" continues through Sept. 4 in the Jefferson Building of the Library of Congress, 101 Independence Ave. SE. It is open Monday through Saturday from 10 a.m. to 5 p.m. The international exhibition was co-organized by the library and the Vitra Design Museum in Weil am Rhein, Germany, where the show premiered nearly two years ago. The library version contains many unique items culled from the more than 2 million documents, photographs and other items bequeathed by Ray Eames.