During this weekend, Zhang Jun's team went to volunteer in a primary school near the Jinshanling section of the Great Wall in Hebei Province.

Actually, Zhang Jun and his teammates spend almost all their weekends on matters related to the Great Wall,though they rarely go to the famous Badaling section in northern Beijing where tourists and foreign heads of state visit.

Zhang's team prefers the sections with steep cliffs, broken walls, and huge piles of rubble that ordinary people would ignore.

"Totally shocked," said Zhang, who was born in south China but became concerned about the man-made marvel, which stretches across north China, when he saw photos of dilapidated sections.

In 1999, a dozen Great Wall enthusiasts like Zhang set up a volunteer team to promote and protect the Great Wall. They also launched a website www.thegreatwall.com.cn to share the information they gathered.

Throughout the years, the team has attracted over 200 members from all walks of life, including a registered accountant, a chemical engineer, a newspaper editor and civil servants.

They started as hikers, walking along the Great Wall in many provinces to enjoy the outdoors. Now, they have become guardians, protecting and preserving the world wonder.

PERSISTENT AMATEURS

"The Great Wall" club values the power of images. They always carry old photos, taken decades or even a century ago, to find the same spots where they were photographed and see the scenery as it appears today.

Unfortunately, through the lenses of today's advanced cameras, the great structure appears as deserted walls, ramshackle towers without roofs, or renovated buildings with modern facades.

"It is a mixed feeling," said "Yeren Laogou" (a nickname), another member of the team. "I was very excited when I stood in front of scenes that appeared in old photos. I felt like I was involved in history, but I also felt very regretful as the Great Wall has changed so much that I could not see yesterday's glory."

The sharp visual contrast has alarmed them, and they take as many photos as possible of the Great Wall so that more records could be preserved.

The group set up an expedition team, invited archaeologists to give lessons, went to libraries and did research day and night for about 10 years.

On their website, the team shares all their research, including maps of many little-known wall sections, data pools of relics, photos, documents and geographical data.

They have even provided visual evidence to relic authorities to assist the protection of Great Wall sections endangered by nature or human activities.