YOU HEAR about an exhibition of oldtime movie theaters called "Palaces of Dreams." So you find the modest Octagon House where, a sign on the wall informs you, the Treaty of Ghent was ratified. Then, as you walk towards the quaint, three-story building you wonder where they're going to house all those towering Art Deco fronts, Babylonian columns and friezes of muscular, naked gods.

The answer is, in snapshots. You won't find the real things. Most of those grand, hyperbolic monuments to the moviegoing imagination, built in the 1920s and 1930s, are long gone, although some have been saved from the wrecking ball and turned into performing arts centers, sports arenas and other "useful" venues. In fact, the only tactile evidence of theater glory here is a shoe-sized, glass-encased piece of ornamental wall plaster; this show documents the work of theater designer John Eberson in photographs and architectural drawings.

Still, those pictures and designs show what deliriously staggering work Eberson did more than half a century ago. Born in Bokovina (now part of the Soviet Union) and a university student in Vienna, Eberson brought a fondness for European opera houses, baroque palaces and landscaped gardens with him to America. He mixed that in with good old immigrant chutzpah and created in the late '20s what he and his collaborator and brother Drew called "Atmospheric Theatres."

Their moviehouses had amphitheater seating, Babylonian pillars, Sistine Chapel-ish friezes. Some were made to look like indoor grottos. There were oversized clocks, crests, shields, statuary and, an Eberson trademark, the dome-enclosed "sky" with moons and stars. Eberson created the Paradise in the Bronx, the Majestic in Houston, Loew's Richmond, the New Majestic in San Antonio and many others. Then, as the silent-movie era gave way to the Jazz Age, the Depression and talking pictures, Eberson embraced Art Deco and made, among others, the Silver Theatre in Silver Spring and the Penn in Washington.

As an accompanying, Smithsonian-produced video-documentary points out, Eberson was but one of many designers who did for Hollywood at the exhibitor end what the Goldwyns and Thalbergs did at the producer end.

From the Roaring Twenties on, these palaces sprung up everywhere, from Canton, Ohio, to Catalina Island; and they weren't just based on European palaces and theaters. There were Mayan temples, Egyptian temples and Persian temples. The reputed inspiration for the 6,000-seat Radio City Music Hall, built in 1932, was a particularly nifty sunset its designer saw one day on an ocean liner trip.

"We sell tickets to theaters, not movies," the famous Mr. Loew stated once, with simple eloquence.

Although two small rooms of photographs can't possibly sum up this crazy, lavish era, it pushes the visitor in the right direction; and it may help remind some of a wonderfully crazy time when you could see the latest Greta Garbo movie, backed up by a live, 50-piece orchestra or Wurlitzer organs rising on hydraulic lifts, with a palatial array of columns, gilded stairs and attendants in braided uniforms. And all this for less than a buck.

PALACES OF DREAMS -- Through Jan. 20 at the Octagon House, 1799 New York Ave. NW. Open 10 to 4 Tuesday through Friday, noon to 4 Saturdays and Sundays. Suggested donation is $2. Metro: Farragut West.