1 / 100 The Great Wall of China

The Great Wall of China is an extraordinary feat of construction, first begun in the 5th century BC, which stretches for more than 5,500 miles. However, many aspects of this description are quite misleading. The only sections of the Wall surviving today have been continuously renovated and rebuilt, and are therefore in fact modern constructions. Furthermore, the Great Wall is not a continuous barrier at all - there are enormous gaps between sections, while others run parallel for many miles. Much of the Great Wall isn't even made of 'wall' at all - instead it consists of geographic barriers: mountains, hills, rivers, valleys and trenches. There is also a myth that the Great Wall is the only man-made structure that can be seen from space, and this too is false. While there is <a href="http://www.snopes.com/science/greatwall.asp" target="_blank">some controversy</a> over whether the Great Wall can be seen from space at all, we do know that it can't be seen from the moon. To be visible from the moon, the Great Wall would have to be about 70 miles wide, whereas in reality it is no more than 10 metres wide at any point. <em>This slide has been updated with additional information about the visibility of the Great Wall from space.</em>