When was Great Wall of china built

The Great Wall of China which is the longest man-made structure ( series of many walls built over time) was built over 2000 years ago around 221 BC.

It was not built in a certain period, but through a long time in many dynasties! As early as the Warring States Periods (476 BC - 221 BC), they started to build walls as a defense against the enemy! Later, the State of Chu, Qi, Yan, Wei, Zhao and Qin all built some sections, followed by Han and Ming Dynasties!