Despite the arduous work, there's a sense of pride. The workers, who can only work on the wall from April to October due to the region's harsh winters, find respect upon returning home. "It's a matter of pride to say they've worked on the Great Wall," Cheng says.

"When they return home in November, they talk to their neighbors. They say, 'I was restoring the Great Wall in Beijing', and everyone admires them. Even though it is tiring and hard, they are still willing to do the job because they love what they do. It takes seriousness, dedication and responsibility to protect the Great Wall properly," he says.

Huang Jiaying contributed to this story.