Great Wall of China, Beijing, China

The Great Wall of China, is a series of fortifications, that were built across the historical northern borders, of ancient Chinese states and Imperial China, as protection against various nomadic groups, from the Eurasian Steppe. Several walls were built from as early as the 7th century BC, with selective stretches, later joined together by Qin Shi Huang (220–206 BC), the first emperor of China. Little of the Qin wall remains. Later on, many successive dynasties, built and maintained, multiple stretches of border walls. The best-known sections of the wall, were built by the Ming dynasty (1368–1644).

Apart from defense, other purposes of the Great Wall, have included border controls, allowing the imposition of duties, on goods transported along the Silk Road, regulation or encouragement of trade, and the control of immigration and emigration. Furthermore, the defensive characteristics of the Great Wall, were enhanced by the construction of watchtowers, troop barracks, garrison stations, signaling capabilities through the means of smoke or fire, and the fact that the path of the Great Wall, also served as a transportation corridor.

The frontier walls, built by different dynasties, have multiple courses. Collectively, they stretch from Liaodong in the east, to Lop Lake in the west, from the present-day Sino–Russian border, in the north to Tao River (Taohe) in the south; along an arc that roughly delineates, the edge of the Mongolian steppe; spanning 21,196.18 km in total. Today, the defensive system of the Great Wall, is generally recognized as, one of the most impressive architectural feats in history.

The sections of the Great Wall, around Beijing municipality, are especially famous, as they are frequently renovated, and are regularly visited, by tourists. The Badaling Great Wall, near Zhangjiakou is the most famous stretch of the wall, for this was the first section to be opened to the public, in the People's Republic of China, as well as the showpiece stretch, for foreign dignitaries.

The Great Wall of China, has been a UNESCO World Heritage Site, since 1987. UNESCO acknowledged it as, the largest man-made structure on Earth. The Great Wall, was declared as one of the New Seven Wonders of the World, in 2007. Every year, more than 10 million people visit, the Great Wall of China, making it one of the world's most popular, tourist attractions.