A dangerous but picturesque section of the Great Wall in Beijing is undergoing renovation after becoming popular among hikers. It had fallen into disrepair after years of natural erosion and human damage.

The Jiankou section of the Great Wall in Beijing’s Huairou district is called the “wild wall” because of its rugged, craggy and sometimes dangerous areas. And its steepness and peril has emboldened many hikers and tourists to climb it.

Built over a range of periods spanning from the third century BC to the Ming Dynasty, which ended in the 17th century, many sections of the Great Wall are in desperate need of renovation. The main damage has been caused by natural erosion, but in recent years, improper behavior by tourists has worsened the situation.

“Some tourists tore down bricks when their way became blocked, like this. The bricks are all gone, only the base is left here,” said Cheng Yongmao, technique consultant, Repair Project of Jiankou Section of Great Wall.

Cheng Yongmao is a descendant of Ming Dynasty construction experts. He has spent the past 13 years studying and helping renovate the Great Wall in Huairou District.

He says the section that needs repair is 1,003 meters long, 30 percent of which has been completed. Transportation is the most difficult part. Vehicles cannot get in, and cattle often takes over, just like in ancient times. And the cost is huge.

“A 1-kilometer-long renovation will cost as much as 20 million yuan. It is very time-consuming and requires a large number of manual laborers to carry new gray bricks and stones up the precipitous mountains by foot,” said Guo Dapeng, deputy head of Huairou Cultural Heritage Committee.

According to the State Administration of Cultural Heritage, about 30 percent of the 6,200-kilometer Great Wall built in the Ming Dynasty has disappeared, and less than 10 percent is considered well-preserved.