The most comprehensive and technologically advanced survey of China’s Great Wall has discovered the ancient monument is much longer than previously estimated, state media reported yestreday.
However the project has also shown the World Heritage-listed site is in danger of disappearing in many places due to road construction and other forms of development, as well as extreme weather, the China Daily said.
The wall, built over centuries to keep foreigners out of China, stretches for 8,851.8km, much further than common estimates of 5,000km, the findings of the survey showed.
The defensive structure includes 6,259.6km of actual wall, plus 359.7km of trenches and 2,232.5km of natural barriers such as hills and rivers.
The two-year mapping project, carried out by the State Administration of Cultural Heritage, involved using global positioning systems and infra-red technology.
Previous estimates were mainly based on historical records, rather than physically mapping each section. By tracking thoroughly across mountains and through deserts, unknown parts were uncovered.
Shan Jixiang (單霽翔), director of the State Administration of Cultural Heritage, was quoted as saying the survey had helped clear up an ancient mystery over its length but also highlighted many problems in trying to preserve it.
“The Great Wall is under great threat, climate change and the country’s massive infrastructure building being the biggest two,” the China Daily quoted Shan as saying.
The first parts of the Great Wall were built more than 2,000 years ago, then rebuilt and extended during the Ming Dynasty amid the threat of invading northern tribes.
In recent times, the wall has suffered extensively at the hands of modern development, with sections of it destroyed to make way for roads and other forms of construction.