The library of Yves St. Laurent and Pierre Bergé's apartment on Rue de Babylone in Paris.. Photo: Christie's

An oval-shaped "Portrait of the Comtesse de La Rue," by Jean Auguste Dominique Ingres, in the living room. Photo: Christie's

Photo: Christie's

"Portrait of Giusto Ferdinando Tenducci," by Thomas Gainsborough, top, and "Nu au bord de la mer," center right, by Henri Matisse. Photo: Christie's

The "Music Room" with 15 mirrors by Claude Lalanne in gilt bronze and galvanized copper. Photo: Christie's

In the foreground, a pair of 1928 seats by Gustave Miklos in leopard skin, palm wood and red lacquered bronze. In front of the mirror is "Portrait of Madame L.R.," an oak sculpture by Constantin Brancusi. Pablo Picasso's "Musical Instruments on a Table" is in the center on the wall; "The Tea Cup" by Fernand Leger is on the wall between the windows. Photo: Christie's

Many of the best pieces were stuffed into their apartment at 55 rue de Babylone in the Seventh arrondissement, but they do not seem at their best there. The walls and floors seem overstuffed and the apartment itself almost airless with excess. Photo: Christie's

Some of the work, like a beautiful Matisse, five Mondrians and three Légers, have been off the market for a long time, so that for some collectors and museums, it's now or never. Photo: Christie's

But what is expected to be the most valuable piece in the collection, a Cubist Picasso from 1914-15, "Musical Instruments on a Table," on the wall at right, is rumored to have been on the market less than two years ago at a higher price. Photo: Christie's

"Portrait of Alfred and Elisabeth Dedreux," by Théodore Géricault, above, and "The Violin," by Juan Gris, center. Photo: Christie's

A large Roman marble athlete's torso, first to second century A.D. Photo: Christie's