Can 18th-century windows find happiness with 21st-century curtains?

They have at the Corcoran Gallery of Art, where the perfect crimson, champagne and cream silks with golden passementerie have just been hung in the Salon Dore.

The curtains, which were woven in France and arrived just before Halloween, are the finishing touch to a decade-long restoration of the antique reception room. They are a fittingly lavish tribute to William A. Clark, the Francophile collector, industrialist and senator who brought the room to America and bequeathed it to the Corcoran in 1925.

The Salon Dore was a model of 18th-century craftsmanship and decor. But its shine was dulled over the decades by grime and inadequate repairs. Beginning in 1990, a ceiling mural of putti amid garlands was revealed after cleaning removed dirt and overpainting. Corcoran art students transformed dove-gray walls to their correct shade of blanc du roi, or "king's white." And skilled French craftspeople from the respected firm of Robert Gohard applied 18th-century skills to repair the damaged gold leaf.

A million dollars later, the windows still were bare.

Corcoran conservator Dare Myers Hartwell, who masterminded the restoration, eventually persuaded an anonymous donor to fund the cost -- estimated at $150,000 -- of dressing three nearly floor-to-ceiling windows and a doorway in keeping with the significance of the room. A French firm that traces its history back to Marie Antoinette's Versailles agreed to weave silks in the old style, adorned with swooping birds, trailing vines, cornucopia, urns, medallions and assorted butterflies. The luxurious lengths of fabric are tied back with what must be Washington's most elaborate gold tassels.

"It's perfect," declared Christian Prevost-Marcilhacy, retired inspector general of historic monuments in France, on a recent visit. The Corcoran's consultant for curtains had come from Paris to assure historically correct details in a project of importance beyond the Corcoran. Only after verifying the precise number of millimeters between curtain and gilding did he proclaim the room perfect and complete.

The Salon Dore ranks as one of the extraordinary surviving environments from 18th-century France. The carved and gilded wall panels were created more than two centuries ago for the Hotel de Clermont, an elegant Parisian residence. The commission came from an ambitious young Count d'Orsay, who wanted his new wife, a princess, to feel at home. By 18th-century candlelight, tall and costly pier mirrors would have reflected gilded "trophy" panels carved with imagery of love, victory, music and the arts. The carvings are among the earliest examples of neoclassical style, which emerged at that time in France.

The young wife died in childbirth. The king and queen succumbed to the mob. The count, who had fled to Germany in the 1780s, lost his property and died in 1809 in a Vienna hospital for the poor.

The house fared better. After the revolution, it was turned into a gymnasium; the panels survived. After a century or so, they were removed and sold. Clark acquired them for his Fifth Avenue mansion in New York, and they came to rest at the Corcoran. (Copies were made and installed in the Paris house, which is not far from the Rodin Museum.)

Whatever its meaning to Clark, the room occupies an essential place in French decorative history, Prevost-Marcilhacy notes.

"The room is an excellent ambassador of French art," he says. "In the history of French rooms, it is very spectacular."

Regilding and painting at the Salon Dore took 8,246 artisan-hours, using rabbit glue, spit and garlic along with 30,000 gossamer sheets of yellow and green gold leaf. No similar restoration could be undertaken in France today, he says, because of the cost. At Versailles, all funding is going to restore the park, which was ravaged by a storm that uprooted 10,000 trees in December 1999.

But French craftspeople still possess rare knowledge when it comes to simulating the atmosphere of the ancien regime. When Hartwell approached the Tassinari & Chatel fabric house about making fabric for the curtains, she brought with her a drawing by the Salon Dore's architect, Jean-Francois-Therese Chalgrin. The 1774 design was fine, but not Hartwell's supposition that the fabric would have been plain red damask. For one thing, the French experts pointed out, "damask" was used to describe various fabrics in the 18th century. For another, plain red would have been much too "sad" for such a room. Hartwell selected a pattern from their voluminous 18th-century archives. The champagne butterflies make all the difference.

So much attention to interior finery is quite in keeping with Clark's legacy. The Salon Dore was the receiving room of the copper baron's mansion, on which he lavished "more money than has ever been spent on a house in America," according to an account from the World magazine of 1905 now on display at the Corcoran. The house would not be as large as those of the Vanderbilts and the Astors, nor would it have the most land. But in "costliness of materials, perfection of workmanship and elaborateness of decoration, none of these approaches it."

Unlike the Salon Dore, the house did not long survive its creator's passing. It was torn down in 1927 and replaced with an apartment building.

The Corcoran Gallery of Art's Salon Dore is open during museum hours. William A. Clark's collection is being celebrated through Feb. 4 in the show "Antiquities to Impressionism." The museum, at New York Avenue and 17th Street NW, is open daily from 10 a.m. to 5 p.m. and until 9 p.m. on Thursdays. Closed Tuesdays. Adults $5, families $8, seniors and students $3, students 13-18 $1. Free Mondays and Thursday evenings. Call 202-639-1700.

Sabastien Ragueneau, of the French firm A la Maniere de Sieur Bimont, which made the curtains, steamed them, left, then hung them, below, with Bimont head Michel Chauveau, on ladder.