Aerial photo taken on Nov. 20, 2021 shows the Grand Baoen Temple Heritage and Scenic Area lit up blue to celebrate World Children's Day in Nanjing, east China's Jiangsu Province.Photo:Xinhua

Aerial photo taken on Nov. 20, 2021 shows the Grand Baoen Temple Heritage and Scenic Area lit up blue to celebrate World Children's Day in Nanjing, east China's Jiangsu Province.Photo:Xinhua

Aerial photo taken on Nov. 20, 2021 shows the Yinpenling Bridge lit up blue to celebrate World Children's Day in Changsha, central China's Hunan Province. Photo:Xinhua

The Simatai section of the Great Wall is lit up blue to celebrate World Children's Day in Beijing, capital of China, Nov. 20, 2021.Photo:Xinhua

Aerial photo shows the Shengjing Grand Theater lit up blue to celebrate World Children's Day in Shenyang, northeast China's Liaoning Province, Nov. 20, 2021.Photo:Xinhua

Children from Shenzhen in south China's Guangdong Province and South China's Hong Kong sing songs to celebrate World Children's Day at a lighting ceremony in Shenzhen, Nov. 20, 2021.Photo:Xinhua