Lincoln Center unfurled giant screens across the facade of the Metropolitan Opera House, as though Christo were starting to wrap the building, and rallied almost 2,000 of New York's wealthy, powerful, talented and interested in evening dress for its 20th birthday party Monday night.

The food, drink, dancing and music came in all styles in the 14-acre West Side cultural center, which replaced slums that in turn had replaced the farmland New York's early settlers had called Bloomingdale.

The Emerald Society Bagpipers played "Give My Regards to Broadway," Peter Duchin played for dinner dancers and the vigorous discoed into the morning on the stage of the Vivian Beaumont Theate, surrounded by 3,000 yards of Mylar (silvery vinyl), which led John W. Mazzola, president of Lincoln Center, to joke about the troubled theater reopening as a discotheque.

Edward Villella, principal dancer with the New York City Ballet, took a look at the packed stage and remarked, "If they could get this many people to come to the performances they would play 20 years."

Gov. Hugh Carey received congratulations on the birth of a grand-daughter and proclaimed once again that he loves New York.

China's deputy representative to the United Nations, Lai Ya-Li, favored the roast beef hors d'oeuvres while violinist Itzhak Perlman made for the clams and oysters. Perlman said he planned to drop out early from the party, which lasted until 2 a.m., to hear the end of Berlioz' Requiem, being performed at Carnegie Hall.

For the partygoers it was a moveable feast. From the Beaumont stage to the central courtyard to the elegantly set tables in Avery Fisher Hall and the New York State Theater, and back in to disco on the theater's stage for cabaret and more food at the Juilliard School.

Mr. Vladimir Horowitz, Sir Rudolph Bing, Stephen Smith, Judy Collins, Gloria Vanderbilt (who discoed with singer Bobby Short), Rise stevens, Mayor Edward Koch, former mayors Abraham Beame and Robert Wagner were among the guests who filed by the ice sculpture "20s" and a glass-protected birthday cake desiigned by painter Larry Rivers. The cake portrayed the Center's three principal buildings, courtyard and fountain.

A sound and light show of highlights of the first 20 years, projected across the Center's courtyard onto the giant screens, was the evening's centerpiece.

It began as President Eisenhower's groundbreaking for the Center 20 years ago had, with Aaron Copland's "Fanfare for the Common Man." Colored spotlights played from the roofs of the New York State Theater and Avery Fisher Hall, the courtyard's fountain gushed upward and the uncommon men and women guests settled onto folding chairs to watch brief filmed glimpses of the musicians and dancers who have drawn about 52 million people to 31,000 performances at the Center.

It rained on Eisenhower and his chrome-plated shovel 20 years ago, but with age came better luck, and the predicted showers held off, enabling Lincoln Center officials to keep furled the 2,000 see-through umbrellas they had ordered, and to breathe more easily.

The umbrellas, lettered "Happy Birthday Lincoln Center," will be sold in the Center's gift shop.

Images of Sutherland, Pavarotti, Baryshnikov, Bernstein, Makarova and dozens of others, larger than ever projected before, covered the screens, recolling luminous performances past and bringing applause from the guests, many of whom had been there when.

The celebration was not so much of the artists, however, as of the buildings themselves. Lincoln Center was the last great building project of Robert Moses, driven to completion under John D. Rockefeller III. The first cost estimate was $75 million; the final bill when it was completed in 1969 was $161.5 million.

It was a celebration, as well, of New York as a cultural center. Felix Rohatyn, the investment banker who has just agreed to another effort to save New York City's financial situation, called it symbolic.

"Philosophically, when you see this," he said of the celebration, "How can you see this city going bankrupt?"

Henry Geldzahler, the city's commissioner of cultural affairs, joked on the same theme: "The United States without New York is Canada."

Mayor Koch went global. New York, he said, is the cultural center of the world largely because of Lincoln Center.

Mazzola and Lincoln Center's chairman, Amyas Ames, took the occasion to stress that Lincoln Center has had an economic as well as cultural impact on New York.

The sound and light show, which will be projected on the same screens once an evening throughout the summer for the public, begins with pictures of some of the dilapidated buildings that stood on the site 20 years ago.

Center officials and their gursts, who paid $250 a ticket to attend the party, also could laugh at the famous acoustical problems of Philharmonic Hall. After years of unsuccessful tinkering, a wholesale interior renovation financed by Avery Fisher improved the acoustics and brought about a name change. Philharmonic Hall became Avery Fisher Hall.

Lincoln Center's other long-running problem has been the short runs of several companies that have tried to mount plays in the Vivian Beaumont Theater.

A new effort is being organized, but for almost two years the huge stage, which served as cocktail party forum and then discotheque last night, has been dark. While the theater has continually hemorrhaged money, the elegant pool in its fore-court leaked the water in another of the Center's building pains.

For all its troubles, including a continuing and probably endless need to raise money, Lincoln Center's achievements have been extraordinary. In its 13 halls of all sizes, people can find music and dance of dazzling quality and variety 12 months a year.

Judging from the guests' reaction to the show and the crowded dance floors in three of its buildings last night, Lincoln Center also knows how to give a good party.