THE REAL "Rosebud" sled from "Citizen Kane." The boots Gary Cooper wore in "High Noon." The scarecrow costume from "The Wizard of Oz." And the actual Alien Ship from "Close Encounters of the Third Kind."

It may have been only a movie, but these are the real thing.

What fantasy and fluff await in "Hollywood: Legend and Reality," at the Museum of American History.

After a brief stint in New York City, the dream factory went Hollywood 70 years ago with silent movies, and it continues to shoot for the stars -- though Garbo has been replaced by C-3PO and Elizabeth Taylor by E.T. "Hollywood: Legend and Reality" attempts to encompass all that, and put it in perspective -- an ambitious venture worthy of a Cecil B. DeMille -- with about 200 photos and as many artifacts.

But no exhibit -- and not radio, TV, nor even VCRs -- can rival the cinematic scope of the giant screen. In this show, relics of the Silver Screen turn out to be smaller than life. For example, the puppet that scaled the Empire State Building: Fur missing, the little monkey looks like someone's cat has been playing with it. Alas, King Kong, they should've used a peashooter. And how could that piano from Rick's Cafe in "Casablanca" be so small and still play it again, Sam?

The exhibition is divided into seven sections, each with its own marquee and movie theater or video monitor. The distant din of seven movies playing at once gives you the persistent feeling of standing in the back of a theater. These film clips whet the appetite for the classics -- Fred Astaire spinning Ginger Rogers, a shoot-'em-up in "Scarface" (the old Howard Hughes version). Flapping from "The Birds" competes with Brando's "I could've had class. I could've been a contender . . . " and Gloria Swanson's "I am big. It's the pictures that got small."

And there is a movie buff's wish list of publicity stills, fanzines and some smashing movie posters and memorabilia. On a giant poster for 1925's "The Phantom of the Opera," Lon Chaney's ghostlike arms envelop the Paris Opera as it burns. One from Germany shows Dietrich as a "Blonde Venus," revealingly draped, and Fatty Arbuckle's fat face grins from a French poster. Here is the matador's "suit of lights" Valentino wore in "Blood and Sand," and the gown Mae West wore in "I'm No Angel," eliciting delicious cries of moral indignation. And Scarlett O'Hara's cameo, and the Best Picture Oscar won by "Gone With the Wind."

The exhibit gives glimpses of what goes on behind the glitter -- contracts and controversies, the "Production Code" of censorship in the '30s, the House Un-American Activities Committee hearings in the late '40s and early '50s.

And it reaches into the backlots to take the mystery out of special effects. Getting into several layers of reality here, on a fake "movie set," among the 50-year-old props is a tall sailing ship used in the 1935 "Mutiny on the Bounty." For those who believe everything they see, it was for long shots, to give the illusion of sailing on the horizon. The same principle applied 45 years later with the bike bearing a small E.T. and Elliott that is displayed here.

Be prepared for disillusionment as well on seeing the miniature Gozer Temple from "Ghostbusters," the rotating-head dummy from "The Exorcist," and the gilded suit worn by the actor who played C-3PO in "Star Wars."

The Smithsonian Institution Traveling Exhibition Service has organized the exhibit, and Time Inc. has financed it, as well as opening its photo archives to it.

Their show is destined for stardom.

HOLLYWOOD: LEGEND AND REALITY -- At the Museum of American History through June 15.