BEIJING, June 7 (UPI) -- China's existing Great Wall, one of the country's treasures, is 13,170 miles long, much longer than a previous survey showed, officials said.
Survey results released Tuesday by the State Administration of Cultural Heritage show the wall to be considerably longer than the 5,500-mile figure a preliminary survey in 2008 showed, China's state-run Xinhua news agency reported.
Great Wall structures span the country's 15 provinces, autonomous regions and municipalities, the survey found.
The survey identified stretches of the wall, defense works and passes, as well as other related Great Wall facilities and ruins, Tong Mingkang, SACH deputy chief, said.
Construction of the Great Wall began in the Warring States Period, 475-221 B.C., and more of the wall was added by later dynasties in scattered but strategic areas to fend off northern nomadic tribes.
Cultural heritage officials say the Great Wall is still threatened by natural forces as well as human activities, as only 8.2 percent of the wall built during the Ming Dynasty remains intact, 74.1 percent is in poor condition, and in some sections only its foundation remains.
The five-year survey gives the cultural heritage administrative department and local governments "a comprehensive and accurate picture of the status quo of the Great Wall, which could serve as a solid foundation for future protection projects," Tong said.