The following information is NOT printed on this postcard: The Great Wall of China, is a series of stone and earthen fortifications in northern China, built, rebuilt, and maintained between the 5th century BC and the 16th century to protect the northern borders of the Chinese Empire. Since the 5th century BC, several walls have been built that were referred to as the Great Wall. 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 were built during the Ming Dynasty. 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. 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). Laozi, Laosi; also Lao Tse, Lao Tu, Lao-Tzu, Lao-Tsu, Laotze, was a philosopher of ancient China and is a central figure in Taoism. Laozi literally means "Old Master" and is generally considered an honorific. Lao-tzu is revered as a deity in most religious forms of Taoism. According to Chinese tradition, Lao-tzu lived in the 6th century BC. Historians variously contend that Lao-tzu is a synthesis of multiple historical figures, that he is a mythical figure, or that he actually lived in the 4th century BC. A central figure in Chinese culture, both nobility and common people claim Lao-tzu in their lineage. Throughout history, Lao-tzu's work was embraced by various anti-authoritarian movements.