What did you do for Christmas? I spent it at David and Julia Koch’s palatial apartment, drinking Dom Perignon and snacking on caviar and foie gras alongside Barbara Walters, Glenn Close, Princess Firyal of Jordan, and Tory Burch. Okay, not exactly—I was with my family on the actual holiday. But no offense to my parents and their lovely spread, last night, it felt like Christmas all over again.

The occasion was a cocktail party celebrating the release of French Impressions, an album by Grammy Award-winning violinist Joshua Bell and pianist Jeremy Denk. An ulterior occasion was the opportunity to view the Kochs’ multi-level Park Avenue apartment—a small part of it, anyway—a fact not lost on the security man in the lobby who sternly instructed that no photographs of any kind be taken of the rooms.

No problem, I was too busy gawking at the vestibule, larger than many a studio apartment and decorated for the holidays by Bronson Van Wyck with garlands of brown magnolia leaves (not a single one curled out of place) and a two-story Christmas tree decked with real stuffed white birds, including an enormous peacock.

Mr. Koch greeted guests with a handshake as white jacket-clad waiters passed out freshly carved ham on biscuits, caviar served from an endless supply of tins, and glasses of vintage champagne, which they refilled with abandon.

“This is a nice potluck,” quipped one girl.

A library held not only books but also two Renoirs and what appeared to be a Degas sculpture. A larger room was hung with a vast array of nautical landscapes. “I have one of the largest private collections of Joseph Vernets,” said Mr. Koch to Karen LeFrak, referring to the 18th century French painter. As they admired one such canvas occupying an entire back wall, Koch added, “That’s from an auction a year ago. Most people don’t have that large a wall.”

Bell and Denk gave a “petit concert” for guests in the same room, which was furnished with rows of couture-style gold-legged chairs—sample size bodies only, please. The floor soon filled with Muffie Potter Aston, Christine Schwartzman (presumably, she took an elevator from her apartment in the same building to get there), Christine Baranski, Carolina Herrera, and, rather curiously, Naomi Watts and husband Liev Schreiber, both dressed in more casual gray garb.

“How did they end up here?” asked one guest of the ultra-liberal actors. The same could be said of Gayle King, who arrived in a clingy teal number and vertiginous matching python heels. Keith Lieberthal—his wife Julianna Margulies was busy shooting The Good Wife—was abstaining from alcohol that night, but wondered if he shouldn’t “make an exception for Dom” before saying with a smile, “at least I can have caviar.”

Bell and Denk gave a half hour-long performance of such vigor and skill that it received two standing ovations and left the violinist dripping. “The amount of effort you put in… we have a shower upstairs if you’d like to use it,” joked Koch as he congratulated Bell. Earlier, during his performance, Bell had commented, “I think this is the first house I’ve played in that’s worth more than my violin.”

Afterwards, as some guests lingered to chat and catch further glimpses of the apartment’s many rooms, Bell admitted to feeling a few nerves, though “surprise friends like Glenn Close and Liev Schreiber” helped ease them.

“When Barbara Walters is two feet away from you…well, she doesn’t come over for tea, so she’s a little intimidating,” he said.

Photos: Patrick McMullan