Great Wall of Han Dynasty

The Great Wall of China was continuously built during the Han Dynasty (206BC-220AD). It was extended towards the west to Lop Nur Lake in today's Xinjiang Uygur Autonomous Region. And an outer Great wall was added to the north of the Qin Great Wall. With its system of fortifications and beacon towers, the Han Great Wall reached a total length of about 10,000 kilometers.

Tang Great Wall
With the expansion of the Tang Empire (618-907AD), the frontier was pushed further north, and the Great Wall ceased its function for almost 300 years.

Since the Han, various dynasties, including Northern Wei,Eastern Wei, Northern Qi, Northern Zhou, Sui, Liao, lin and Ming, rebuilt the Great Wall on extensive scale. The engineering projects undertaken in the Ming dynasties were the largest.

Tang, Yuan and Qing dynasties, which did not undertake construction of the Great Wall on any large scale, nevertheless repaired the passes and fortresses and made use of them. It may be said, therefore, that the Chinese governments never interrupted defence work over the Great Wall in the course of more than 2,000 years.