Repairing centuries of damage to the Great Wall of China is no easy task. (Which, of course, makes sense when you consider that the wall took more than 1800 years to erect.) Since 2005, workers have carried out grueling—and often, life-threatening—physical labor to see that the World Wonder is restored to the same tiptop shape it was in during the Ming dynasty.

Most recently, restoration efforts have been focused on the Jiankou section of the wall. The re-bricking process requires that workers dangle from a single rope, held by their teammates, while they coat the wall in cement. The faintest slip of the hand could cost them their lives.

As if the physical demands weren't enough, the laborers are also burdened with the responsibility of maintaining historical accuracy. Last year, preservationists were outraged by the "botched" repairs made to the Great Wall in northeast China. "A once unkempt, haunting 700-year-old stretch of the wall now looks like a cement skateboarding lane dumped in the wilderness," The New York Times wrote at the time.

New video footage from Live China—and spotted by National Geographic—gives an up-close view of this physically demanding work, as well as the process of transporting bricks via donkeys and mules. You can watch it in full below: