Great Wall of China
Designated as a UNESCO World Heritage Site in 1987, the Great Wall stretches from Lop Lake in the west to Dandong in the east, along an arc that almost delineates southern edge of Inner Mongolia. A thorough archaeological study concluded that most of them were from the Ming dynasty and measure about 8,850 km: 6,259 km are sections of actual wall; 359 km are trenches; and 2,232 km are made up of hills and rivers.
The walls were built as early as 7th century BC with purpose of protecting Chinese empires and states against invasions of many nomadic groups from the Eurasian Steppe region. One by one the states joined together to build larger and stronger walls. Another purpose of building this wall was for border controls, such as the imposition of duties of goods, regulation of trade and control of both immigration and emigration.
The most popular sections where you can enter the Great Wall from Beijing are Badaling, Mutianyu, Junshanling and Simatai, located in the suburbs about 64 to 145 km from central Beijing.