A Chinese archaeologist has revealed that the Great Wall of China has several parallel walls, contrary to the popular perception that views the structure as a single continuous block.

The Great Wall was originally built in the Warring States Period (475 BC - 206 BC) to defend China from nomadic tribes.

The Great Wall’s survey team Director Duan Jingbo revealed that several sections of the structure have shown two to three smaller walls which are built parallel to the main wall, Xinhua reports.

He said a section of the wall located in Shaanxi province is composed of two parallel walls, which made it more defensive and thus helped military leaders to garrison troops more effectively.

The Chinese government began an intensive Great Wall survey in 2006, to investigate the overall condition of the structure.