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 to protect the Chinese states and empires against the raids and invasions of the various nomadic groups of the Eurasian Steppe with an eye to expansion. Several walls were being built as early as the 7th century BC; these, later joined together and made bigger and stronger, are collectively referred to as the Great Wall.

While portions north of Beijing and near tourist centers have been preserved and even extensively renovated, in many other locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads. Sections of the Wall are also prone to graffiti and vandalism, while inscribed bricks were pilfered and sold on the market for up to 50 renminbi. Parts have been destroyed because the Wall is in the way of construction.

A 2012 report by the State Administration of Cultural Heritage states that 22% of the Ming Great Wall has disappeared, while 1,961 km (1,219 mi) of wall have vanished. More than 60 km (37 mi) of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In some places, the height of the wall has been reduced from more than 5 m (16 ft 5 in) to less than 2 m (6 ft 7 in).