Architectural drawings are the one true record of the castles in the sky of the architect's mind. That's because rarely does any building make the transition from paper to bricks and mortar without changes. It is the architect's sketch that preserves for us the original design, unsullied by tightfisted clients, inept contractors and sloppy workmen.

Some buildings called "paper dreams" by critic Wolfe Von Eckardt in the introduction to the catalog of the current exhibit of drawings and other items at The Octagon - exist only on paper. Yet they may have a real life and influence on the work of others.

Many architects are remarkably fine artists, and they are employers of fine artists. And so architectural drawings of subjects from the villas of Venice to the skyscrapers of New York are important art works. They show us not only what another age considered workable, but also what it thought beautiful.

The Octagon exhibit, "Selections from the American Institute of Architects Architecturals Archives," was put together by Joan Steiner and Rhoda Sterling. George Washington University graduate students interning in The Octagon's museum program. The show, will remain at The Octagon, 1799 New York Ave., through Sept. 13.

The exhibit is important largely because of the tantalizing taste it gives us of the AIA Archives. The boxes upon boxes, books upon books of material, have long been stacked in untidy piles in storage. Only a portion is catalogued. Little has been easily available to the student.

In June, the AIA board of directors voted to transfer the administration of the archives to the AIA Foundation, directed by Jeanne Butler. The College of Fellows has allocated a $7,500 seed grant to begin cataloguing, inventorying and conserving the archives.

The most extensive of the collections are those given by Richard Morris Hunt, the 19th-century architect who designed such American palaces as The Breakers in Newport, R.I., represented in the exhibit by an ink sketch and a watercolor draeing.

Another delight in the exhibit is the color drawing of The World's Columbian Exposition Administration Building in Chicago.

There are three noteworthy sketches of the north wing of the U.S. Capitol by two architects of the Capitol, Ammi B. Young and Thomas Ustrick Walter. The drawings of the ceiling of the old Supreme Court in the Capitol, by Glenn Madison Brown, would have been very useful during the recent reconstruction, had they been found earlier.

One high art modern style drawing is the ink-on-linen of The Octagon's entrance by Brown, who wrote a monograph on the historic house when it was AIA headquarters. (AIA still preserves The Octagon but has offices in a new building behind.)

Besides drawings, the archives include letters, records and even drawing instruments.

The show does not pretend to be exhaustive. It is designed only to arouse our appetites for serious study of this treasure trove.

The future of the AIA archives is clouded. Many people hope the archives, properly catalogued, conserved and studied, will form the scholarly foundation for a museum of the building arts proposed for the Pension Building by Von Eckardt and associates. Butler says some consideration has been given to dispersing at least part of the collection - the drawings of the Capitol, for instance, could go back to the Capitol.

The current exhibition does exactly what it was designed to do - make you want to dive into those pasteboard boxes and find out what treasurers are there.