Researchers are to carry out the first detailed survey of the Great Wall of China to establish just how long the ancient barricade is, Xinhua reports.
The structure is a series of walls first linked up over 2,000 years ago
Along with checking its dimensions the four-year study, which starts in May, will map the wall's exact route.
And it will check the condition of the fortification, built to protect the northern border of the Chinese Empire.
The wall, the world's largest man-made structure, is estimated at over 5,000 kilometres (3,100 miles) in length.
The study will be conducted by the State Administration of Cultural Heritage and the State Bureau of Surveying and Mapping in 13 provinces, regions and municipalities, the Xinhua official news agency said.
Archaeologists had lobbied for the survey to be done to provide scholars with an accurate understanding of the construction.
Known to the Chinese as the "long Wall of 10,000 Li", the Great Wall is in fact a series of walls and earthen works begun in the 5th Century BC and first linked up under Qin Shi Huang in about 220BC.
It was listed as a Unesco world heritage site in 1987.