China's long history has left many cultural relics and the title of "China Top Tourist City" has gone to the first group of 54 cities. The Great Wall, a symbol of the Chinese nation, is also a prime example of historical sites that have become major tourist attractions. As the greatest defense-structure project in the history of human civilization, it dates back more than 2,000 years ago to the Spring and Autumn and the Warring States periods - huge in its scale and grandeur. There are more than ten sections of the Great Wall open to tourists, including the passes, blockhouses and beacon towers at Badaling in Beijing, Laolongtou in Hebei and Jiayuguan Pass in Gansu.