Tourists pose for photos on the 100-meter-long and 1.6-meter-wide glass bridge built on the cliff of the Tianmen mountains in Zhangjiajie scenic area, Hunan province, on August 1, 2016, as the third glass bridge in the scenic spot opens to the public on Monday. Walking on the high-altitude glass bridge, people can enjoy the dizzying view of the "heaven-linking Avenue", the twisting mountain road from the foot of the mountains to the Tianmen Cave. [Photo/VCG]