An aerial photo taken on May 17, 2016 shows the nearly finished construction site of a glass bridge at the Grand Canyon of Zhangjiajie National Forest Park, central China's Hunan Province. The 430-meter-long, 6-meter-wide bridge is expected to be put into a trial operation in May. The structure has undergone nearly 100 safety tests to ensure that it can support the weight of 800 people. (Xinhua/Long Hongtao)