Nearly four months after the Tall Ships sailed home, the last Elvis impersonator swiveled offstage, and Battery Park was cleared of garbage -- and precisely 100 years since President Grover Cleveland dedicated her -- the Statue of Liberty observed her actual centennial with a simple ceremony today.

"We had enough gala celebrations on July 3, 4, 5 and 6," said Armand Avedisian, chairman of the Statue of Liberty-Ellis Island Centennial Commission, at a preceremony reception. "Today will be a bit more -- I won't say solemn, but more low-key."

Among the 1,500 people gathered on sun-washed Liberty Island for the program were members of the commission and the Statue of Liberty-Ellis Island Foundation, a Masonic delegation in embroidered aprons and medallions (Masons raised $ 2 million for the statue's restoration), members of assorted Veterans of Foreign Wars posts and their ladies' auxiliaries in blue pillbox hats, 500 moving and storage company executives affiliated with Allied Van Lines (a corporate sponsor) and several individuals who had saved last summer's green foam crowns and statue earrings for just such an occasion.

They listened to speeches by the French minister of culture and communications and Secretary of the Interior Donald Hodel, among others, and heard Secretary of the Treasury James Baker announce that to date, the sale of Liberty coins has raised $ 68 million, the largest single source of funds for the restoration project.

The birthday was not entirely untouched by pomp, of course. Monday, on Ellis Island, special Ellis Island Medals of Honor were presented to an astonishingly eclectic group (selected by the National Ethnic Coalition of Organizations after complaints about the narrow ethnic mix of last July's 12 Medal of Liberty recipients). Among the 56 medalists who braved the drizzle to accept the award were Joe DiMaggio, Donald Trump, Cesar Chavez, Rosa Parks, Anita Bryant and Muhammad Ali. (Among the 24 no-shows: Jacqueline Onassis, Martina Navratilova and Arnold Palmer.) Recipients celebrated at a banquet at the Waldorf-Astoria that night, featuring a 5 1/2-foot red, white and blue cake aflame with 100 candles. Bob Hope cut the first slice. The hoopla was to continue at Lincoln Center tonight with a black-tie musical gala.

Nor was the event untouched by politics. Hodel took the opportunity to deliver, along with lengthy paeans to freedom, a blast at the Soviet Union's "systematic and continuous abuse of the rights of its citizens," praise for President Reagan's "moral leadership" and a plug for the Star Wars defense system -- necessary, Hodel asserted, "so that ... liberty does not depend solely on the threat of nuclear retaliation." The secretary gestured toward an empty chair, "symbolic of the millions and millions of people throughout the world who yearn for freedom."

Hodel's blasts did not extend to his one-time nemesis, Statue of Liberty-Ellis Island Foundation Chairman Lee Iacocca, however. Despite their well-publicized differences last summer, despite Iacocca's absence from the ceremony today (though he was invited) and despite Hodel's avoidance of the Ellis Island and Waldorf events (he pleaded prior commitments), the secretary said after the ceremony that the two "get along well" and would both attend the Lincoln Center concert.

The last event of the centennial will be the sealing -- sometime after Dec. 31 -- of a time capsule, to be stored in the museum at the statue's base unopened until her bicentennial in 2086. Along with such items as tape-recorded oral histories from immigrants, videotaped highlights of Liberty Weekend from ABC News and messages from Hodel and Reagan, the capsule will contain centennial memorabilia and a "Take Pride in America" pin.

That still may not be the last word, however. Renovation is continuing at Ellis Island, the north end to be completed in 1988. The southern end, its fate undecided, may become a park or a privately financed learning/conference center, but in any case is expected to be completed in time for the island's centennial in 1992. While he knew of no additional ceremonies planned "at this time," Hodel said, "I hope the celebration of liberty in this country goes on forever." And it seemed that it might.