Preserving the Great Wall no easy task

Meandering on mountain ridges across northern China, the Great Wall, one of the world's man-made wonders, has for thousands of years protected residents from invasion. Gone are the beacons and soldiers on the mountaintops, but another group of rangers has appeared, protecting the ancient landmark from a new kind of invasion.

In Yanqing district, on the northern outskirts of Beijing, home to a 179-kilometer section of the Great Wall, a team of more than 60 government rangers and some 200 volunteers are ensuring that destruction of the wall by humans is halted once and for all.

Mei Jingtian, 73, is the oldest of them. He lives near Badaling, where the oldest sections of the Great Wall date back to the Northern Qi Dynasty (550-557). "I grew up at the foot of the Great Wall. It was an important part of my childhood," he said.