The sky-high glass-and-iron domed Grand Palais is a Belle Epoque architectural spectacle in itself. As for the auction, its being trumpeted as the sale of the century, expected to fetch up to $432 million. That mega-figure dwarfs Sotheby’s Jackie O sale, which rang up $34 million, and the Bill Blass auction, which made a "mere" $13.7 million. Prices at the Paris sale are expected to go through the roof and trump any notion of a downturn. Part of the proceeds go to a new foundation dedicated to scientific research and the fight against AIDS, says Bergé.

Visiting the apartment at 55, rue de Babylone, where St. Laurent lived from 1969 until last June (he died at age 71), was like stepping into a home of unimaginable sophistication, filled with rarities most Americans have no knowledge of, like Limoges enamels, Roman cameos and Renaissance silver. The setting reflected a rarefied sensitivity to living with art and antiques. The paintings alone are to die for: early Mondrians, five Géricault works, an astonishing Degas landscape, six Légers, a sublime Cézanne watercolor, the Goya that is to be a gift to the Louvre.

The collection runs the gamut across cultures, centuries, styles and eras. Five-star Old Masters share the space with antiquities and Art Deco furniture. The red lacquered entry hall designed by Jacques Grange (whose redesign of the Mark Hotel in New York opens in March 2009), with its glimmering domed gold ceiling, signaled a kind of magic, but the interiors never exuded brazen hauteur.

Yet overall, St. Laurent’s apartment, which lay hidden behind anonymous doors on the Left Bank, was much like the designer himself: He was reclusive, belying a dazzling creative mind that produced a profound and lasting impact on fashion. His collection, which he formed with Bergé over five decades, is bound to make a similar impact in the art world, ratcheting up the very notion of collecting and prices in the art market, too.

Some of the world’s most discerning masters of taste, such as the architect Robert Couturier, have gone on record praising the apartment and its contents. "It showed vast intelligence, a very varied sensibility and an incredible pair of eyes," said Couturier. "It is refined, a universe in itself of esthetic perfection."

There’s a sense of comfort in the home right down to the white cotton slip-covered sofas and the books that were actually read, yet the designer himself said one factor distinguished their holdings: "quality being the only criterion to guide us."

Among the highlights:

Lot 50, Pablo Picasso, Instruments de musique sur un guÈridon, 1915, est. €25,000,000-€30,000,000 (ca. $31,500,000-$37,900,000). This Synthetic Cubist still-life is bound to be the mega-painting of the sale. Great structure, fascinating palette, sky-rocketing price. It had been rumored to have been on the market during the last days of the designer’s life.

Lot 77, Jacques-Louis David, Portrait d’homme de profil, 1795, est. €400,000-€600,000 (ca. $515,000-$772,000). Some of the offerings are so laced with history, they’re spellbinding. Of particular note is David’s pen-and-ink self-portrait. Highly sculptural in its treatment, this work had been owned by Edmond and Jules de Goncourt. The presale estimate makes a $1 million painting by Damien Hirst seem pure frivolity.

Lot 83, Théodore Géricault, Portrait de jeune garcon de profil, 1815-17, est. €400,000-€600,000 (ca. $515,000-$772,000). Several Géricault portraits of children are on the block. Not one bit capricious, the portraits are haunting and surprisingly grave with a Neo-Classical kind of monumentality that prefigures Corot’s more statuesque portraits. The painter’s 1818 Portrait d’Alfred et Elisabeth Dedreux is pegged to make $5.2 million-$7.7 million.

Lot 93, Edward Burne-Jones, L’Adoration des Mages, 1904, est. €400,000-€600,000 (ca. $515,000-$772,000). In a demonstration of their immunity to fickle fashion, YSL and Bergé favored tapestry. On offer is Sir Edward Coley Burne-Jones’ The Adoration of the Magi from 1904. While Burne-Jones rendered the subject both in stained glass and paintings, this example is more massive in scale. It had been executed for Guillaume Mallet’s Edwin Lutyens house near Dieppe and later successfully hidden from the Nazis. Even if it goes for over its presale high estimate, this tapestry from an edition of ten will still be a relative bargain, as this specialty is finally back again in vogue.

Lot 220, Claude Lalanne, Ensemble de quinze miroirs aux branchages, 1974-85, est. €700,000-€1,000,000 (ca. $884,000-$1,260,000). Music rooms by and large are a snore, with chipped harpsichords, dusty harps and the odd violin, but YSL and his partner upped the glam factor and laced their music salon with mystery by commissioning 15 cast bronze mirrors accentuated by candelabra, all cast in serpentine plant forms by Claude and François-Xavier Lalanne. When lit with dozens of candles, the effect can only be described as intoxicating and more Bavarian Baroque in feel than the Versailles Galerie des Glaces. Unlike the sometimes trite and pedestrian output of the Lalannes, these mirrors are grand in scale.

With designers expected to fight over these mirrors, they could go way over the presale high estimate of €1,000,000.

Lot 243, Eileen Gray, Enfilade, ca. 1915-17, est. €3,000,000-€5,000,000 (ca. $3,790,000-$6,300,000). Yves St. Laurent favored Art Deco furnishings and among his stellar examples is this Eileen Gray sideboard. Examples by Gray, especially large pieces of furniture, are exceedingly rare. This one carries a double fashion world provenance, since it was commissioned by the French designer known as Suzanne Talbot in 1915. The upper section is in gray lacquer speckled with silver while the lower portion is sheathed in reddish brown lacquer. The bronze fittings are decorated with animal designs.

Lot 252, Gustave Miklos, Paire de Banquettes, ca. 1928-29, est. €2,000,000-€3,000,000 (ca. $2,526,000-$3,790,000). Enriched by more than just the YSL provenance, this petite pair of benches by Gustave Miklos (1888-1967) owes its importance to another fashion legend. Paris couturier Jacques Doucet commissioned them from the young Hungarian for his revolutionary and stylish studio. Remarkably simple in form, the benches are spiked with coral-painted feet and handles. St. Laurent had them reupholstered with exotic leopard skin.

Lot 292, Jean Dunand, Deux Vases Monumentaux, 1925, est. €1,000,000-€1,500,000 (ca. $1,260,000-$1,900,000). Dunand was a master extraordinaire at lacquer. His 1925 pair of monumental vases could soar way over the presale high estimate to set a new auction record. Historically important, they were originally a set of four designed specifically for the influential 1925 Exposition Internationale des Arts Décoratifs et Industriels Modernes in Paris.

Lot 129, Bateau en vermeil et argent, 1609-29, est. €30,000-€50,000 (ca. $38,000-$63,000). Ingenious silver gilt was another passion of this collecting couple. This model ship encapsulates all the inventiveness and skills of its maker, Esaias zur Linden of Nuremberg, Germany. The bell-shaped base is chased with waves and spirited dolphins while the hull is engraved with a frieze and the billowing sail consists of striped panels of silver and pale gold. The sale also includes a set of silver gilt flatware: over 1,000 pieces.

Lot 300, Maurice Marinot, Flacon et son bouchon "soleil," 1928, est. €6,000-€8,000 (ca. $7,600-$10,000). The auction includes "smalls" like chunks of rock crystal, but even they will soar in price. This example, just over four inches high, a glass bottle by Maurice Marinot (1882-1960), is a treasure and looks like it was carved out of amber with a stylized sun pattern on each side. Any of the five Marinot bottles would be a superb acquisition.

Postscript: Unfortunately, only 7,000 copies of the five-volume boxed catalogue, priced at $290. It has already sold out and is on its way to becoming a collectible in its own right.

If you miss both the sale and the catalogues as well, in November, Christie’s Paris is selling the contents of Yves Saint Laurent’s Chateau Gabriel, which is located in Deauville.

BROOK S. MASON is U.S. correspondent for the Art Newspaper, and also writes for the Financial Times and other publications.