A two-year government mapping study has found that China’s Great Wall is longer than previously believed, the BBC reported, citing state media. A study carried out by the State Administration of Cultural Heritage and the State Bureau of Surveying and Mapping found that the iconic Great Wall spans 8,850 kilometers, compared to previous estimates that put the wall’s length at around 5,000 kilometers. The study, the first detailed survey of its kind, used infrared and GPS technologies to locate some sections of the wall that had been hidden by sandstorms. Much of the newly-discovered sections of the wall were built during the Ming Dynasty and stretch from Liaoning to Gansu province. The survey will continue for another 18 months to map sections of the wall built in the Qin and Han Dynasties.