Great wall of China

                                                    The Great Wall of China was built over more than two thousand years. Construction on the first section began between the 7th and 6th century BC, and the last work on the wall was done between the 14th and 17th centuries.

                                                         The Great Wall of China is a series of stone and earthen fortifications in northern china, built originally to protect the northern borders of the Chinese empire against intrusions by various nomadic groups. Several walls have been built since the 5th century BC that are referred to collectively as the Great Wall, which has been rebuilt and maintained from the 5th century BC through the 16th century. One of the most famous is the wall built between 220–206 BC by the first emperor of china , qin shi huang. Little of that wall remains; the majority of the existing wall was built during the ming dynasty

                                          

         The Great Wall stretches from Shanghaiing in the east, to lop nur in the west, along an arc that roughly delineates the southern edge of inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has recently concluded that the entire Great Wall, with all of its branches, stretches for 8,851.8 km (5,500.3 mi). This is made up of 6,259.6 km (3,889.5 mi) sections of actual wall, 359.7 km (223.5 mi) of trenches and 2,232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.