In the rugged mountains of the Tianzhu Tibetan autonomous county in Gansu province, where the Great Wall snakes across the peaks, 68-year-old Wang Xilin has spent more than three decades on patrol, helping ensure the architectural wonder's preservation for future generations.

"During the past 30 years, I've heard only my footsteps and the howling wind while walking in the wild mountains. At first, I was lonely, but each mound of earth has become an old friend," Wang says, adding that he feels it is his family duty to guard the structure for generations to come.