Great Wall of China is now LONGER!

Over 2,200 years after it was built, China's Great Wall continues to be a mystery, as new studies reveal that it could be almost 2.4 times longer than originally measured.

Archaeologists and mapping experts have found 43,721 sites related to the Great Wall structure crisscrossing the country, making its overall length to be at 21,196.18 km, according to the latest survey published by China's State Administration of Cultural Heritage.

"The previous estimation particularly refers to Great Walls built in the Ming Dynasty (1368-1644), but this new measure includes Great Walls built in all dynasties," Yan Jianmin, office director of the China Great Wall Society, an NGO founded by specialists and scholars to protect the Great Wall, told state-run China Daily.

Qin Shi Huang, the first emperor of the Qin Dynasty (221-206 BC), was famous for building the Great Wall, the world's largest human-made structure.

But construction of the wall had begun as early as 7th century BC, the new survey said.

The oldest section of the Great Walls that have been found is the Great Wall of Qi State in Shandong province and the Great Wall of Chu State in Henan province. Both date back to the Spring and Autumn Period (770-476 BC), according to Yan.

"As thousands of years pass, some ground structures disappear, and we do not know where the walls used to be. When some local governments or companies develop the land, like for coal mining or building new roads, they destroy the remaining parts under the ground," Yan said.

"Now we are clear about the location of the Great Wall, so the government can take steps to protect the walls, and local governments are clear about their responsibility to protect the walls," he said.