The Great Wall of China is immediately recognizable in this shot...One of the lesser-known facts about the Wall is that its main function was not to physically stop northern "barbarians" from entering China. It is clear that although the wall is 5-8 meters (10-18 feet) tall, it is possible to scale for any determined enemy force. The main function of the wall was to act as a massive guard post and means of communication in case of such an invasion. The watchtowers were guarded, and signal fires and smoke signals were used to signal enemy presence. The messages were passed from tower to tower, reaching generals faster than any messenger could...The Great Wall is now a UNESCO World Heritage Site, and it is a fitting symbol of Chinese unity and longevity. This shot is striking for me as it gives a glimpse into the incredible hardships humans had to endure to build over 6000 kilometers (4000 miles) of the wall. Although the Great Wall is, well, great, it is minute compared to Mother Nature's creations.