Mules carry bricks for the repair work of a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018. （Photo: Xinhua）

Workers repair a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018.

Aerial photo taken on Aug. 22, 2018 shows a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China.

Staff members measure and make analysis of a tower at a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018.

Mules carry bricks for the repair work of a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018.

Aerial photo taken on Aug. 22, 2018 shows a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China.

Workers carry bricks for the repair work of a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018. A section of the Great Wall here was severely ruined due to man-made and natural factors, and the repair and reinforcement work has started this year.

Aerial photo taken on Aug. 22, 2018 shows a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China. A section of the Great Wall here was severely ruined due to man-made and natural factors, and the repair and reinforcement work has started this year.

Aerial photo taken on Aug. 22, 2018 shows a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China. A section of the Great Wall here was severely ruined due to man-made and natural factors, and the repair and reinforcement work has started this year.

A worker carries bricks for the repair work of a section of the Great Wall constructed in the Ming Dynasty (1368-1644), north of Donggou Village in Miyun District of Beijing, capital of China, Aug. 22, 2018. A section of the Great Wall here was severely ruined due to man-made and natural factors, and the repair and reinforcement work has started this year.