Tourists pose for a photo at the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China, March 29, 2023. (Xinhua/Chen Zhonghao)

This aerial photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Zhang Chenlin)

This aerial photo taken on March 28, 2023 shows the Shuiguan Great Wall in Beijing, capital of China. (Xinhua/Ju Huanzong)

This aerial photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Chen Zhonghao)

This photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall in Beijing, capital of China. (Xinhua/Zhang Chenlin)

Tourists visit the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China, March 29, 2023. (Xinhua/Zhang Chenlin)

A train runs amid blooming flowers near the Juyongguan section of the Great Wall in Beijing, capital of China, March 23, 2023. (Xinhua/Chen Zhonghao)

This aerial photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Zhang Chenlin)

Tourists visit the Mutianyu section of the Great Wall in Beijing, capital of China, March 29, 2023. (Xinhua/Ju Huanzong)

This photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Chen Zhonghao)

This aerial photo taken on March 29, 2023 shows a boat sailing at the foot of the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Chen Zhonghao)

This aerial photo taken on March 29, 2023 shows the Huanghuacheng Lakeside Great Wall Reserve in Beijing, capital of China. (Xinhua/Zhang Chenlin)

This aerial photo taken on March 28, 2023 shows the Shuiguan Great Wall in Beijing, capital of China. (Xinhua/Ju Huanzong)

This aerial photo taken on March 28, 2023 shows the Shuiguan Great Wall in Beijing, capital of China. (Xinhua/Ju Huanzong)

Tourists visit the Mutianyu section of the Great Wall in Beijing, capital of China, March 29, 2023. (Xinhua/Ju Huanzong)