The Great Wall dating back to the Qin Dymasty is one important part of the world's heritage. It's purpose is to defend the country from invasion, during whose building a lot of loss was caused to the wealth of the country and the lives of people. It is said that the Great Wall is the only man-made project that can be seen from teh moon. The Great Wall with its long history and its magnificence attracts a lot of tourists and scientist to pay it a vist.