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. China's National Cultural Heritage Administration has vowed to strengthen the protection of the Great Wall, which is more than 21,000 km long. The Great Wall, a UNESCO World Heritage Site, consists of many interconnected walls, some dating back 2,000 years. (Xinhua/Luo Xiaoguang)