A year after buying The Plaza in 2004, Elad sold the hotel portion back to Alwaleed Bin Talal, the Saudi prince from whose partnership the company bought it. The prince will run the hotel through his Fairmont Hotels chain.
Kaplan said the hotel would open by the end of the year.
Many of the world's rich and famous stayed at The Plaza through the decades, and dozens of movies have been filmed there, including ''North by Northwest,'' ''Funny Girl'' and ''Barefoot in the Park.''
''It's synonymous with celebrity,'' said Ward Morehouse III, author of ''Inside The Plaza.''
The Beatles took a whole wing in 1964, and Truman Capote hosted his Black and White Ball, hyped as the party of the century, there in 1966. Author Kay Thompson enchanted readers with Eloise, a little girl who lived at The Plaza.
Not that living there was restricted to fiction; in that sense, The Plaza's new identity as a condo-hotel hybrid is true to its past.
Morehouse said his father, theater critic Ward Morehouse, lived at The Plaza for about a dozen years in the 1950s and '60s and half the rooms were occupied by full-time residents then.
''Marlene Dietrich lived there,'' Morehouse said. ''Frank Lloyd Wright lived there during the construction of the Guggenheim.''
Designed by Henry Hardenbergh, the architect of the Dakota apartment building and the Art Students League in Manhattan, The Plaza is a French Renaissance structure that evokes a chateau on Central Park South.
''It's a wonderful white sugar cube of a building,'' said Christopher Gray, an architectural historian who writes a column for The New York Times real estate section and remembers sneaking up the back stairs into debutante parties in the Grand Ballroom in the 1960s.
The Plaza's 100th birthday party included a speech by singer Paul Anka, fireworks and a light show.
The cake was a 12-foot scale model of The Plaza meticulously crafted by society baker Ron Ben-Israel, who said the cake was baked in sections Sunday and Monday to ensure freshness, while the sugar shell was fabricated over several weeks.