Constructors work at the construction site of Taizicheng tunnel of Beijing-Zhangjiakou high-speed railway in Chongli District of Zhangjiakou City, north China's Hebei Province, on August 11, 2017. Two years after Beijing and Zhangjiakou successfully bid to host the 2022 Winter Olympics, Chongli District, where most skiing events will be held, experienced a busy and colorful summer. (Xinhua/Mu Yu)
