New York is on the cutting edge of party innovation. Take the housewarming, a form of celebration that has probably existed since cavemen lit their first torches.

Under the venerable tradition, as soon as the boxes are unpacked, proud new homeowners or renters put out cheese dip for neighbors bearing gifts, such as woven potholders and houseplants.

In New York, the housewarming has evolved considerably. These days, the party happens before anyone has even moved in.

Celebrities, models, and financiers are drinking, nibbling, and even smoking in as-yet-unsold homes that even they would gasp to live in: the city’s hottest new luxury residences.

There are plenty of reasons for this. To start out, novel spaces for parties are hard to come by. Furthermore, party planners know that most people will choose a party in a home over any other, because they promise an intimate, personal experience – even if no one actually lives there. Then there’s the fascination with real estate in this town, and the people’s eagerness to be the first to see it.

All those forces came together Wednesday night on the fifth floor of 165 Charles St., the Richard Meier-designed glass box overlooking the Hudson River. In a model unit with a modern look, courtesy of furnishings from Troy and contemporary art from the Lehman Maupin Gallery, the building’s developer, Izak Senbahar, smiled ear to ear as he greeted Gwyneth Paltrow, Iman and David Bowie, Edie Falco, Damon Dash, Todd Meister, and a hundred other social, fashion, and film VIPs. If any of the guests decided to buy in the building, they’d be joining Natalie Portman. Calvin Klein and Nicole Kidman both have places next door.

It was a most excellent housewarming, with candles lit around the bathtub and sinks, and with attentive bartenders and waiters, supervised by Olivier Cheng. Chinese takeout is available, too, as Lauren Bacall discovered when the actress asked Jamie Figg, who is in charge of sales at 165 Charles St., what was in the brown bag he was holding. His answer: an eggroll.

Mr. Senbahar, whose co-developer is Simon Elias, made a special point of showing the artist Anh Duong the doors to the bathrooms and closets. The doors, which Mr. Meier designed, cost $6,500 each.

Other important points about the homes: The exterior walls really are floor-to-ceiling glass. The views are serene, even though the West Side Highway is right below. The balcony fits only about 10 people comfortably. And the most popular space in the apartment would clearly be the living room and the open kitchen. No one stayed for long in the bedrooms, although a few visitors did test the beds, which were decked out in fine linens.

As is often the case at New York parties, the party wasn’t just a housewarming. Dior and Andrew Saffir’s Cinema Society put together the bash to toast Ms. Paltrow on her new film, “Proof,” which opens this weekend. The film’s director, John Madden, and its producers Jeff Sharp and John Hart were among the guests, although, sadly, not any of its other actors.

It was by far the most exciting and exclusive party of Fashion Week, and it is likely to be remembered as one of the best parties of the year. But don’t feel left out. You, too, can throw a party in the building, scheduled for occupancy in a few weeks. About 10 units are available. The one the party was in is priced at $5,450,000.