Reporting from Beijing -- For Bonnie Burnham, it was like entering a Chinese version of an Egyptian tomb.

On a cool autumn day in 1999, the president of the World Monuments Fund followed her guides into an area where few had set foot since 1924, when China's last emperor vacated the palace and locked the doors to the studio behind him.

What she remembers most is the musty air and thick coat of dust that covered the floor, the delicate pieces of furniture, the lushly paneled walls etched with courtly lines of calligraphy.

"There was a sense that time had stopped there," she recalled.

On Monday, Burnham stood among dignitaries from the Forbidden City's Palace Museum to unveil the refurbishment of one of the most historically important interiors to survive from China's imperial past.

The tiny two-story lodge known as Juanqinzhai, a window into the private world of one of the Middle Kingdom's most artistic emperors, will soon be open to the public.

The $3-million restoration, which took nearly a decade to complete, marks an extraordinary partnership of Chinese artisans and Western expertise -- a rare instance in which China sought foreign assistance and know-how to restore one of its precious historical treasures.

The results have been so successful that the World Monuments Fund, a private, nonprofit New York-based preservation group, is extending its alliance with Chinese cultural officials to restore the Qianlong Garden's 26 other pavilions and four courtyards.

The face-lift's first phase involved detailed excavations of the studio's interior, trips to the U.S. by Palace Museum staff for strategy sessions and a nationwide search in China for artisans capable of the delicate renovations.

"None of us had any kind of road map. Neither the Chinese nor the American side had any experience with this specific type of restoration," said Nancy Berliner, the curator of Chinese art at the Peabody Essex Museum in Salem, Mass.

The Juanqinzhai studio, a two-acre private retreat nestled in the northeastern corner of the Forbidden City, was built in the 1770s by the Qing dynasty Emperor Qianlong for personal use after his retirement.

He called it the "Studio of Exhaustion From Diligent Service."

Its construction occurred when China was engaged with the West in trade and the exchange of aesthetics and ideas. In 1793, Qianlong received a delegation from the court of Britain's George III.

"No resource was spared. Every inch of design and creation was overseen by the emperor himself, who issued an edict that nothing could be altered by future generations," said Henry Tzu Ng, the World Monument Fund's executive vice president.

The result is widely considered a masterpiece of design and materials: a jewel box replete with large murals, elaborate ceiling paintings and ornate flourishes of bamboo, white jade and satin.

Never open to public view, the studio fell into disrepair after China's last emperor, Puyi, was ordered from the Forbidden City in 1924. For decades, including during the Communist takeover and Cultural Revolution, the emperor's refuge became a decrepit storage space.

In many places, the regal wallpaper hung in tatters. Paintings were peeling off the wall. The silk murals were torn from heat and cold. Many of the bamboo-embroidered panels had detached, and wood and jade littered the floor.

For the World Monuments Fund, the forlorn studio was an opportunity. Seeking projects within China, the group approached Palace Museum officials about a restoration partnership.

To their surprise, the Chinese said they were open to outside guidance and funding.

"The Forbidden City is huge and . . . there was too much work to do; therefore, our country didn't have the energy, time as well as enough money to manage this part of the palace," said Wang Shiwei, senior engineer of the Palace Museum's historical architecture department.

"It is the first time the Palace Museum is cooperating with a foreign organization to repair its facilities comprehensively."

Palace officials visited the Peabody Museum and other venues to view firsthand U.S. techniques of restoration.

The pressure was palpable. "It was like restoring something on the level of Notre Dame, something that's been there for centuries," said Berliner.

Back in Beijing, teams of Chinese artisans began work in 2002 that Ng describes as "above-ground archaeology."

Preservationists scoured the studio for every scrap of loose paper and bits of wallpaper and disintegrating mural that had fallen to the floor. Each was sealed in a plastic bag and labeled. Soon, they had amassed 35,000 plastic bags, officials say.

"The last emperor closed the door nearly a century ago," Ng said. "What we found was peeling wallpaper, incredible artifacts, furniture, objects behind objects, all as if he had just left it. There was this incredible sense of discovery."

One day, Burnham recalled, she opened a box she found sitting on a table. "Inside was this exquisite jade Buddha," she said. "There was no sense of how much time had passed. Had that piece been sitting there for 200 years? Or had it been more recently stored there?"

The studio's murals presented a particular challenge. Fashioned under the guidance of Giuseppe Castiglione, a Jesuit missionary and painter who settled in China in the 1700s, the ceiling murals were painted on silk wallpaper, a combination of European aesthetics and Chinese decorative arts seen nowhere else in the entire nearly 180-acre Forbidden City.

Neither the Chinese nor Americans were sure how to remove the wallpapers for restoration. The Chinese first tried to wet the seams. When that didn't work, the Americans introduced a dry method of scraping the fragile wallpaper from behind.

That worked, Ng said. But it didn't solve the challenge of getting the wallpaper back up.

"There were no records of how the wallpapers had originally been stuck, so the Chinese conservation team tried one method and the Western consultants tried a different way," Ng recalled. "We worked out a compromise between the two: We put mattresses on the floor, on top of which we placed poles with tension springs to hold the wallpaper in place until it dried."

In the end, both sides are satisfied with the result.

Said Wang: "I think the emperor would be pleased."