Badaling; Great Wall of China

The Great Wall of China is a series of stone and earthen fortifications in China, built, rebuilt, and maintained between the 5th century BC and the 16th century to protect the northern borders of the Chinese Empire during the rule of successive dynasties. Several walls, referred to as the Great Wall of China, were built since the 5th century BC, the most famous being the one built between 220 BC and 200 BC by the first Emperor of China, Qin Shi Huang. That wall was much further north than the current wall, built during the Ming Dynasty, and little of it remains.

The Great Wall is one of the existing megastructures and the world's longest human-made structure, stretching over approximately 6,400 km from Shanhai Pass in the east to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. It is also the largest human-made structure ever built in terms of surface area and mass. In 1987, the Wall was made a UNESCO World Heritage Site.

-Wikipedia