A ceremony is held to celebrate the completion of an undersea tunnel of the Hong Kong-Zhuhai-Macao Bridge on an artificial island, July 7, 2017. The main structure of world's longest cross-sea bridge linking Hong Kong, Zhuhai, and Macao was finished on Friday. The main structure measures 29.6 kilometers, consisting of a 22.9-km bridge section and 6.7-km underground tunnel. The bridge's total length is 55 kilometers. It has taken seven years to build the bridge, which will be open to traffic at the end of the year. (Xinhua/Liang Xu)