The Great Wall of China is the world’s longest defensive wall along the northwest of the People’s Republic of China. Its length together with the demolished parts is 8851.8 kilometers. Between 221 BC and 608 AD, it was started to stop the raids of the Great Hun Empire. It is a Unesco World Heritage Site. It was also chosen as one of the Seven Wonders of the World. The photo was taken by Paulo Marcelo Martins.