The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China in part to protect the Chinese Empire or its prototypical states against intrusions by various nomadic groups or military incursions by various warlike peoples or forces. Several walls were being built as early as the 7th century BC.
In an archaeological survey that took five years to complete, China’s State Administration of Cultural Heritage announced yesterday that the wall measures 21,196.18 km (13,170.69 miles).
Only 8.2% of the wall built during the Ming Dynasty remains intact, 74.1% is in poor condition, and in some sections, only its foundation remains, according to the report. A large amount of the wall has collapsed.