How Long Did It Take to Build the Great Wall of China?

The earliest known sections of the Great Wall of China were constructed in the 7th century BC. The wall was not built in one go, and actually transcended several dynasties. During the Qin Dynasty (221-206 BC), the Great Wall of China became a collective entity. The wall has been upgraded, enlarged and enhanced since then, the first time around 1700 years after the Qin era.