Four Generations Living Together in a Siheyuan, May 2006.It takes many years to have four generations yet the old courtyard is still their home.[Photo by Bai Hao/For chinadaily.com.cn]

"I like the snow and rain," says Bai. "You can feel the serenity of this city on such occasions."

Until recently, he stuck to film photography rather than digital devices because the film rolls are suitable to capture history, he says.

All the exhibited photos were taken before 2008, when the Beijing Olympics was held.

"After the Games, consciousness about the protection of hutong and siheyuan rose greatly. The layout of the ancient city has been basically kept. Many sites are well preserved," says Bai.