"If this wall falls down I'm going to fall right with it, "warned the guest of honor after two unfailingly cheerful nonstop hours of greeting people he knew, people he didn't, and a few in between.

By that time, Milton S. Kronheim Sr., 90 years old yesterday and proud of it, had shaken, thumped and kissed a collection of hands, backs and cheeks including those of Mayor Walter Washington, retired U.S. District Judge John Sirica, parking lot magnets Dominic Antonelli, yestaurateur and hotel man Ulysses ("Blackie") Auger, Giant stores founder N. N. Cohen, former city police chief Maurice Cullinane, shopping center builder Charles E. Smith and former presidential aide Gen. Harry Vaughn, among hundreds of others.

"I'm feeling pretty good," said Kronheim, dressed in a "Number 90" football jersey. "This is exhilarating."

"You've got everyone here from justices of the Supreme Court to doormen," said Mickay Goldberg. The Supreme Court justice was Thurgood Marshall - William Brennan also was expected - and there were quite a few doormen in attendance from the Mayflower Hotel, where Kronheim lives.

Along the walls of the corridors and offices of Kronheim's wholesale liquor company, hundreds on hundreds of plagues and photographs told the story of a businessman who had completedly immersed himself in the political, social and philanthropic life of Washingotn.

One framed newspaper clipping told of a 1959 baseball game in which a team of former sandlot players called the "used to be's" beat the "has been's" by a score of 7 to 2. Kronheim was the winning pitcher. Another story reported the establishment of a new town in Israel dedicated to Kronheim. A scroll proclaimed his honorary membership in the Ancient Order of Hibernians.

There were photographs of Jack Dempsey, Hubert H. Humphrey, Harry S. Truman, Richard M. Nixon, and John F. Kennedy. "Every president since Roosevelt knew him by his first name," said Goldberg.

Richard Kronheim, who now runs the family liquor firm at 2900 V St. NE, attributed his grandfather's financial success to "his policy toward human beings . . . doing the right thing for the big guy and the small guy."

"My grandfather has always been deeply involved in the community," the grandson added. "The reason is he's enjoyed it."

The community returned the favor yesterday. Mayor Washington, bounding to the front of the line of well-wishers, handed Kronheim, a small box, and muttered, "Just a little something."

"It's good for you to come," said the newly proclaimed nonagenarian.

"Wouldn't miss it, wouldn't miss it," replied the mayor.