8 Marvels of the World
The Great Wall is the most important architectural structure ever built, in terms of length, surface area and mass.
It stretches over 6,200 kilometres, with walls averaging six to seven metres high and four to five metres wide. Intended to protect China's northern frontier, it starts at the border with the coast north of Beijing and extends to the Gobi Desert. Its construction dates initially from the 3rd century BC to the 17th century. Since 1987, the Great Wall has been classified as a UNESCO World Heritage Site.