Another beautiful day in New York. The kind where, if you’re like me, walking the dogs down by the riverside, sun glistening, light breeze gusting here and there, you say aloud: what a beautiful day, and for a moment there everything is All Right.

At about six-thirty I went over to the Fifth Avenue apartment of Georgette Mosbacher where she was throwing a cocktail/book party for Michael Gross and his new tome 740 Park Avenue; The Story of the World’s Richest Apartment Building (see NYSD 10/4/05) which is one of the most interesting non-fiction books you’ll ever read about New York society in the last 75 years.

Mrs. Mosbacher, the cosmetics and skin-care tycooness, invited 200 of the most prominent talkers, opinion-makers, blabbermouths and social gadflies, along with their best friends, acquaintances and the people who make up the media. Very smart, Mrs. Mosbacher, she is. Because practically everyone in the room is dying to read the book to find out if Michael Gross wrote what they already know (but wouldn’t tell him), and just exactly where he drew the line in revealing the “inside” on all the families that have lived in this famously sought after residential building that sits on the northwest corner of Park Avenue and 71st Street.

Jackie Onassis’ grandfather James T. Lee built it, beginning in the same year she was born (1929) and completing it two years later when the world had fallen apart and a lot of the formerly rich were still jumping out windows. Nevertheless, like Scarlett and Tara, the sun did come up tomorrow, paving the way for all kinds of new family sagas (including Jackie’s parents Janet and Jack Bouvier who lived there briefly, thanks to the generosity of Mr. Lee), most of which, like all family stories, are gone with the wind.

There were a number of people at Mrs. Mosbacher’s quite palatial apartment who either lived in the building or were related to those who lived in the building. Dasha Epstein, the Broadway producer lived there from the late 1950s through the early 1970s. David and Julia Koch have just moved in. Alice Mason, the absolute empress of private residential real estate brokers had a hand in the puchase and sale of several of the apartments (and sometimes the same apartment more than once). Jesse Araskog and her husband recently sold their co-op there. Diana Quasha who recently sold her 720 Park Avenue apartment lived at 740 before that. Kathy Steinberg, the sister-in-law of Saul Steinberg, was the broker on both sides of the deal when Steve Schwarzman paid $31 million to buy the old John D. Rockefeller Jr. apartment from Mr. Steinberg. Dominick Dunne never lived there but more than one character in his novels has lived in a buildling Just Like It (fiction, of course).

In many ways, New York is a small town, and like all small towns, there are the pieces of real estate (the biggest house in town, for example) that stimulate interest, envy, greed, and all the other Machiavellian traits that taunt our psyches at one point or another. 740 Park is the place that frequently haunts the dreams of the must-haves in Manhattan.

The fabulous Mosbacher digs had more than enough room (and then some to go around) for the clamoring crowd last night, and so many of them knew each other, or knew of each other, or always wanted to know each other. So it was like Old Home Week visits Lifestyles of the Rich and Famous (without what’s-his-name’s bellowing voice to distract).

There will be discussions for some time as to whether or not Michael Gross was fair or mean to the tenants of the building. It doesn’t matter. As I’ve written here before about his book, it is a testament to the fact that all gossip ultimately becomes history, even, alas, the stuff that’s not true.