As we explore the Great Wall of China, the largest and most widely distributed cultural heritage site in the world, it’s important to understand its significance. Spanning over two thousand years and tens of thousands of miles, the Great Wall embodies the resilience and patriotic spirit of the Chinese people. It stands as a representative symbol of the Chinese nation and an important emblem of Chinese civilization.
So, just how long is the Great Wall? How was its length measured? Where does it extend geographically? What is its state of preservation? And what new methods and philosophies for protection have emerged? In today’s episode of “Cultural China,” we delve into the remarkable stories behind the Great Wall.
Recently, a 40th anniversary event themed “Love China, Restore the Great Wall” took place in Beijing’s Yanqing District, organized by the National Cultural Heritage Administration. Experts and scholars from various cultural heritage departments, universities, and research institutions engaged in extensive discussions about methods and philosophies for preserving the Great Wall.
Liu Wenyan, Deputy Director of the China Cultural Heritage Academy and the National Cultural Park Protection Research Institute, stated, “For the first time, we have clarified the foundational data of the Great Wall. By combining traditional archaeological approaches with modern surveying techniques, we’ve established its total length to be 21,196.18 kilometers. We now also know the locations and conservation status of various remains, allowing us to achieve a significant understanding of the wall’s defensive system. With this knowledge, we can implement refined management practices to enhance the quality of preservation.”
With over 20,000 kilometers of the Great Wall, a rigorous and scientific evaluation system has been developed for its segmentation and marking. Experts have identified approximately 43,000 remains along its journey.
Liu explained, “We follow specific segmentation principles. For instance, when there’s a change in material, we create a new section. Gaps also warrant segmentation, and different historical periods naturally correspond to different segments. This allows us to categorize the wall into diverse portions.”
The Great Wall has endured for more than 2,000 years, from the feudal conflicts of the Spring and Autumn periods to the unification of China by Qin Shi Huang, and through the continuous repairs and expansions during the Ming and Qing Dynasties. It features a rich variety of structures, including watchtowers, beacon towers, and fortresses, making it a magnificent architectural wonder and an unparalleled cultural landscape in human history.
Winding through rugged mountains, the Great Wall is vulnerable to rain erosion. Monitoring shows that rain can significantly damage earth-constructed sections, causing cracks and holes that may ultimately lead to collapse. Through long-term field investigations, experts have discovered that certain surface algae can protect the rammed earth from rain damage. After screening various algae species, filamentous blue-green algae were identified as effective in forming a protective biological soil crust, which has now been successfully cultivated on the surface of the rammed earth sections.
Liu Liang, Director of the Rock and Soil Innovation Center at the Eighth Geological Team of the Hebei Provincial Geological Mineral Bureau, noted, “This is a section of rammed earth wall, where the dark green biological soil crust effectively prevents rain erosion. The filamentous blue algae can intertwine with the soil. Additionally, these algae secrete polysaccharides that bind soil particles, creating a spatial network structure that provides excellent protection for the rammed earth wall.”
Moreover, a new patrol robot is currently in development. This innovative machine can navigate the Great Wall and its watchtowers independently, utilizing advanced technologies like 360-degree imaging, lidar, and infrared monitoring, which will significantly improve both the efficiency and quality of preservation efforts. The focus is shifting from “rescue preservation” to “preventive preservation.”
Liu Wenyan emphasized, “The philosophy of restoration adheres to minimal intervention, which means we try not to alter the current state of the Great Wall and aim to prevent any new risks. The wall was built with the principle of adapting to local conditions, utilizing different materials in various regions. If the rammed earth sections in the west remain towering like those at Badaling, it would contradict natural scientific principles. Just as humans age, the wall naturally wears down. We want to respect its original appearance, as we believe this represents the highest form of respect for both the Great Wall and our cultural heritage.”
