Cheng Yongmao (left) reviews timely the repairs of the renovation project of the east section of Jiankou Great Wall in Huairou district of Beijing. (MA WENXIAO / CHINA DAILY)

With a helmet, a climbing stick and a camera, 64-year-old Great Wall repairer Cheng Yongmao, under the scorching sun, climbed up the Jiankou Great Wall with a history of more than 400 years.

The total length of the renovation project of the east section of Jiankou Great Wall in Huairou district of Beijing is 1,094 meters

In the summer, hidden in range upon range of green hills, it is magnificent for its winding shape that looks like a bow and arrow, and some of the damaged walls exude a sense of vicissitudes. But Cheng had no time to appreciate the scenery.

Despite being listed as one of China's most important cultural heritage site, this section of the Great Wall has been severely damaged by natural erosion and human impact over the years, which is in dire need of maintenance.

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Cheng Yongmao has climbed the Great Wall more than 150 times in recent years. (MA WENXIAO / CHINA DAILY)

The COVID-19 epidemic had put the repair work on the 1,094-meter-long Jiankou section on hiatus for nearly three months. Now, Cheng is working against the clock to meet the deadline by the end of this year without compromising quality.

Starting from the lowest point "Jiankou", Cheng stepped over the potholes of the bricks, over the high cliffs, all the way to the southeast for more than 1,000 meters, until the watchtower "Zhengbei" at an altitude of 990 meters.

Cheng Yongmao (right) talks with backpackers who he meets by chance, and educates them about the idea of cultural relics protection. (MA WENXIAO / CHINA DAILY)

The total length of the renovation project of the east section of Jiankou Great Wall in Huairou district of Beijing is 1,094 meters. Cheng, an engineer of Beijing Huaijian Group, is responsible for the technical guidance. For a man who has been repairing the Great Wall for nearly 20,000 meters in 16 years, this section of the Great Wall is the most dangerous. It is known by hikers as "the wild Great Wall".

"Almost the entire section is on a cliff with a slope of 70 or 80 degrees, It's a mountaineering job, and a oneway trip usually takes at least one hour, so you've got to have good physical strength to repair the Great Wall," he says. To climb the Jiankou Great Wall, one has to climb with both your hands and feet. Despite his years, Cheng insisted on climbing for inspection at least once a week. He could remember concretely every damage on this section of the Great Wall.

A bottle of mineral water and a piece of bread are his lunch routine. (MA WENXIAO / CHINA DAILY)

On the night before leaving for the Great Wall, Cheng was sitting in front of the computer, drawing a detailed sketch of the construction nodes using CAD software. Nowadays, the technical aids and equipment for repairing ancient buildings have made great progress, but the guidelines for reparation have not changed.

Cheng sticks to the reparation principle－minimal intervention－to protect the integrity, authenticity and safety of the Great Wall. Following the original repairing process, he summed up the "five-following" method－following the layer, the slope, the bend, the old and the damage, so as to maintain its ancient style, and pass on the reparation wisdom of the Great Wall to future generations.

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The partially restored Jiankou Great Wall boasts a magnificent view. (MA WENXIAO / CHINA DAILY)

For him, even if hundreds of years have passed, the materials, craftsmanship and methods used in ancient buildings still need to be strictly observed. "As a cultural relics protection worker, it is our responsibility to eliminate the use of materials that are not made according to traditional requirements. We have the responsibility to pass on the cultural relics protection methods and cultural protection spirit from generation to generation," he says.

In 2018, the traditional restoration technology of the Ming Dynasty (1368-1644) Great Wall was included in the sixth edition of the district-level intangible cultural representative heritage list of Huairou.

Cheng climbs up and down repeatedly at some locations to come up with specific repair plans. He sticks to the principle of minimal intervention. (MA WENXIAO / CHINA DAILY)

The inheritance of this technology is currently his most urgent concern as most of the repairers are old, and young people are reluctant to work as bricklayers.

"To make the traditional restoration technology of the Great Wall widely spread, applied, summarized and improved, we need to attract more people to engage in this work, and foster the training culture of relics protection," he says.

Cheng constantly observes and learns the details of the ancient construction, and enriches his historical knowledge in the hope of passing on to his predecessors. (MA WENXIAO / CHINA DAILY)