As of 2014, The Great Wall of China is the largest man-made structure on Earth, stretching over 4,000 miles from the Shanghai Pass to the Bohai Sea. The Great Wall started as individual walls built over several dynasties, but over the centuries, the walls were thickened and joined to form the Great Wall.
The wall started as an effort to protect the historical borders of China against other tribes and nomadic people from the north. There is a section of the wall north of Beijing that is an actual tomb. It holds the remains of 13 emperors and 23 empresses. These tombs each have an underground palace, a Ming tower and a Ling'an hall.