Disused factories and other similar structures are being used to boost tourism, Cao Chen reports in Shanghai.

Old industrial landmarks in Shanghai are magnets for international visitors and a unique driving force for the city's tourism.

Over 700 industrial sites in Shanghai are open to visitors to highlight their production methods and house industry museums, among other things.

"The landmarks recount how our society has changed over time," says Cao Yongkang, director of the International Research Center for Architectural Heritage Conservation at Shanghai Jiaotong University.

"Their structures also possess great architectural, historical, social and scientific value. They're worthy of special preservation and adaptive reuse to optimize what tangible heritage that remains," says Cao.