THE dilapidated building at 173 Shaanxi Road has survived seven decades of turbulent history. Its grimy, neglected walls have witnessed grandeur and war, stories and secrets.

But since the walls can't speak, a group of independent film makers have brought their secrets to light. The result is a documentary/art-house film, "Building 173," that uncovers how residents were caught up in the march of history.

Foreigners, and Chinese too, walk about Shanghai, wondering about the events that took place within historic architecture. But few have the courage and tenacity to knock on doors, talk to people and fly around the world to track down the stories.

The intrepid makers of Building 173 did exactly that.

Entirely self-funded, and as a hobby on weekends, the team of nine researchers, film makers and sound men took a year to piece together the puzzle of the building formerly known as the Cosmopolitan Apartments.

The building is home to 56 apartments which now host 150 families.

It's the story of seven residents over three generations and it marries documentary with cinematic storytelling.

Over the years it was home to wealthy Chinese business families, well-heeled expats, civil servants, a piano teacher and a colorful cast of characters.

The 50-minute film in English was made for just 100,000 yuan (US$14,700).

The film was first screened in Shanghai at the end of April. It was so well received that two more screenings quickly followed. Another is taking place this Saturday.

The film is shown on History Channel (satellite TV), and in overseas film festivals, though not in the Shanghai International Film Festival.

It all started when British TV journalist Charlotte Mikkelborg moved into the building in 2007. Its faded grandeur piqued her curiosity and she got together with Swedish film maker Petter Eldin to do a video investigation.

Dark building

"We hit on the idea to make a film centered on the building. We were both immediately excited by the idea. I had never seen a film like that before," says Eldin.

Eldin came to Shanghai five years ago and teaches multimedia courses while making short films, adverts, and what he calls "comedy sketches," most recently about air guitars.

Mikkelborg is a TV journalist for the BBC who wanted to probe the immense changes in China over the last decades. The old apartment building is a vehicle for that story.

Building 173 today is dark and run down, little remains of the original details and atmosphere.

But it was home to a large cast of characters whose stories woven together form the story of China in the past few decades, and the plot of the documentary.

There is Linda Tan, daughter of a high-society family in old Shanghai that built the Cosmopolitan Apartments in 1934, during a real estate boom. The big Tan family consisted of her father, famed antique collector Tan Jing, four wives, many children and a grandmother.

The Tan's fortunes disintegrated over the last decades. Tan Jing was arrested, the family properties lost, and family members scattered around the world.

Linda Tan, now in her 70s, is living in Canada with her husband, Roger Du, a son of old Shanghai's notorious gangster, Du Yuesheng. She was interviewed in Canada.

The apartments were meant for well-to-do foreigners. American Gregory Patent, now a successful baker and author of children's books, gives a foreigner's view of his childhood in the apartments, and what happened when he came back to China 40 years later.

At the other end of the social scale, Old Liu, an elevator operator, now 95, has spent most of his adult life at the apartments. He left the countryside and went to work at the apartments when he was 23 years old. He recalls vivid details of the people and events in the building, even down to room numbers.

Post-1949, the building was opened to a completely different cast of characters. New residents moved in, and they are represented in the film by three families, from Red Guards to civil servants.

Tales of twisting fortunes followed. During the "cultural revolution" (1966-1976), a piano teacher in apartment 31 put on her best red qipao and high heels and took her own life.

According to Jimmy Fang, the team's Shanghainese-speaking researcher, they talked to 20 distinct households, starting by simply knocking on doors. The search for the right people for the film was not easy, requiring numerous phone calls and resourcefulness.

Linda Tan, for example, was found via a local historian, then via the Shanghai Museum to which her husband regularly donates antiques.

Another lucky find was Old Liu. He retired and lives just 50 meters away from the building, and now runs a corner store.

For film maker Eldin, Liu is the "chaperone" for the disparate threads in the plot line as he had never left China. The film begins and ends with Liu's slow-moving figure.

Linda Tan is the "soul of the film," according to Eldin.

In the film her aristocratic mannerisms, exquisite dress and crisp Mandarin-Chinese hark back to another era. Her experiences also personally moved the film makers. She spoke in Chinese.

Animation effects

"She enjoyed talking to us. She felt it was a kind of retribution and wanted the story told," says Eldin. "But there was no bitterness, just sadness for the breakup of her family."

After 1949, her father was jailed for polygamy (he had several wives) and for taking national treasures abroad.

After he got back from jail, she says in the film, "he was very thin, very old." Then she pauses and says with a smile, "but he was in good spirits."

"That's when we knew she had moved on," says researcher Fang.

But the film is more than interviews with old residents. Animations and sound effects are used to unify the film that juxtaposes the past and present, bringing the now shabby and dull building to life.

Sound is used to good effect - voices, footsteps and echoes reverberate around the empty corridors.

According to Eldin, this places the film somewhere between an art-house film and documentary.

"It's difficult to define this film," says Eldin. "For Charlotte it was about the facts, which comes from her journalistic background. But I was concerned with attracting emotions with picture quality and storytelling."

In the film simple white-line animations of residents long gone populate current footage of the building.

In one scene Tan Jing's old pastime of playing tennis on the roof is revived with the ghostly white lines of animated characters. But now they play against Shanghai's supermodernized skyline.

Superimposed on a background of gleaming skyscrapers and the Yan'an Elevated Road, the scene invites viewers into that space between the past and present.