Rank #20
The Great Wall of China, China
This ancient wonder of the world is one of the most impressive feats of human engineering. The Great Wall of China was built over two thousand years ago and stretches over 5,500 miles along the northern border of China. It was constructed to protect the Chinese Empire from invading forces,
From Wikipedia
The Great Wall of China is a series of fortifications in China. They were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic groups from the Eurasian Steppe. The first walls date to the 7th century BC; these were joined together in the Qin dynasty. Successive dynasties expanded the wall system; the best-known sections were built by the Ming dynasty (1368–1644).