Foreign tourists visit the ancient city wall by bike in Xi'an, northwest China's Shaanxi Province, May 1, 2012. The ancient wall has a history of more than 600 years. High-speed trains linking Xi'an, capital of Shaanxi Province, and Chengdu, capital of Sichuan Province, will begin operation on Dec. 6, authorities said Sunday. With a new train diagram to be put into operation at the end of this year, travel time between the two cities will be slashed by about 7 hours to just 3 hours and 27 minutes. The train service will provide a new choice for tourists to the two provinces. (Xinhua/Li Yibo)