長城 - The Mutianyu Great Wall - Beijing, China
Although walls of defense and of fortification have been constructed in China since the 5th Century BC, the wall that remains and is referred to commonly as the Great Wall was constructed during the Ming Dynasty during the years of 1368 through 1644 AD. The Great Wall stretches from Shanhaiguan in the east, to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. When one considers the combination of the wall itself, natural defensive barriers such as mountains and rivers together with trenches, the total length stretches over 5,500 miles (8,851 kilometers).
Of the Seven Wonders of the World, the Great Wall is the only one which is clearly visible when looking at the Earth from its satellite the Moon.