YORBA LINDA, Calif. — The meeting between two of the most improbable cultural icons of the 1970s lasted all of 30 minutes, but it has fascinated Americans for years.

A photo of a cloaked and bejewelled Elvis Presley solemnly shaking hands with a grim-faced President Richard Nixon remains the No. 1 requested document from the National Archives, nearly four decades after the secret meeting took place on Dec. 21, 1970.

Now, on what would be Elvis's 72nd birthday, the Richard Nixon Presidential Library & Birthplace is giving the curious public a good, long look at the relics of the coming together of The King and The President -- and it's got Elvis fans all shook up.

The free exhibit, which opened Monday and will run several months, includes the outfit Elvis wore (a black velvet overcoat, a gold-plated belt and black leather boots); Nixon's outfit (a grey woollen suit, tie and size 11½ black shoes); letters; and a Second World War .45-calibre Colt revolver that Elvis gave to Nixon.

"The two of them together somehow is almost incomprehensible,'' said Bud Krogh, Nixon's then-deputy assistant for domestic affairs, who set up the impromptu meeting that day 36 years ago. "The king of rock and the president of the United States shaking hands in the Oval Office doesn't compute for a lot of people.''

About 200 people, many of whom arrived early, listened to Krogh reminisce at the exhibit opening.

"Of all the two people, who would ever think that Elvis and Nixon would get together? I couldn't believe it,'' said Gloria Matta Tuchman, 65, of Santa Ana, who said she became enthralled with Elvis as a girl and met him when she was in her 20s.

The chain of events that led to the meeting began when a stretch limousine carrying Elvis pulled up outside the White House. One of his guards handed over a letter from Elvis addressed to Nixon requesting a meeting to discuss how the rock star could help Nixon fight drugs -- including getting credentials as a "federal agent at large.''

"I will be here as long as it takes to get the credentials of a Federal Agent,'' Elvis wrote. "I have done an in-depth study of drug abuse and Communist brainwashing techniques and I am right in the middle of the whole thing where I can and will do the most good.''

At the time, Presley was less than seven years away from an early death at age 42 from prescription drug abuse and heart disease.

The Secret Service agents alerted Krogh, an Elvis fan. Krogh met with Elvis, decided he was sincere and scrambled to get him into a noon meeting with Nixon.

About 2½ hours later, Elvis walked into the Oval Office wearing his flamboyant outfit, as well as sunglasses and two huge medallions. But when Elvis entered the Oval Office, Krogh recalls, he froze.

"I think he was just awed by where he found himself. I ended up having to help him walk across over to the president's desk,'' he said.

Elvis and Nixon talked for about 30 minutes, during which Elvis showed Nixon pictures of his daughter and a pair of cufflinks given to him by Spiro Agnew. He also showed Nixon police badges from around the country and asked again for a badge from the U.S. Bureau of Narcotics and Dangerous Drugs.

Nixon agreed to give him the badge -- but only after learning that the chief of the narcotics bureau had turned down the same request earlier that day and told him the only person who could overrule his decision was the president.

"Oh man, we were set up! But it was fun,'' said Krogh. "He said all the right words about trying to do the right thing and I took him at his word, but I think he clearly wanted to get a badge and he knew the only way he was going to get it.''

At Elvis's request, the meeting remained secret for more than a year -- until the Washington Post broke the story on Jan. 27, 1972.

Since then, the Richard Nixon Library & Birthplace has more than made up for Elvis's ruse: T-shirts, cups, notepads and watches bearing the famous black-and-white photo remain the top-selling items at the museum's gift shop.

"We've known for years that that photograph is an icon image,'' said Sandy Quinn, the museum's assistant director. "It is The President and The King.''