China has an "Great Wall of China" underground from the Three Kingdoms era, used to be a military staple but was not discovered until the 20th century.
In addition to the Great Wall, China has a tunnel thousands of meters long, built by an extremely famous figure in construction history.
In ancient times, the technology was rudimentary, outdated technology, but today's archaeological sites show that what the ancients did was indeed extraordinary. Especially to mention the Great Wall associated with the name of the first Emperor in Chinese history Qin Shi Huang.
But few people know, China even has a tunnel thousands of meters long, and also by an extremely famous figure in history.
Talking about Chinese symbols cannot help mentioning the Great Wall. Many people and even the records in books today claim that Qin Shi Huang was the person who built this wall. However, in fact, some sections of the wall were built before the first Emperor of China ordered to resume and build more from 220 BC and 200 BC, so far only a few relics remain. .
What we still visit today in the Great Wall is mainly built during the Ming Dynasty in 1368-1647.
Like the Great Wall, the underground citadel was also built with the purpose of fighting the enemy. The creator of this tunnel is an extremely famous figure in history - Cao Cao.
Although Cao Cao's people and deeds made many people criticize, he could not deny that he had made great contributions to the country and "underground underground city" was one of them.
Cao Cao built this project not only for the war, but also for his own malice. As we all know, Cao Cao is an exceptionally deep and ambitious person. His goal was not only to unite the Three Kingdoms, but also to dominate Trung Nguyen. To carry out that malice, Cao Cao began to promote the construction of organs above and below the ground, hence the "Great Wall" underground.
Because Cao Cao is not famous as the Great Wall, Cao Cao's "underground city" is less known. Once a film called Dong Tuoc Dai premiered in 2012, the content of the film focused on the story of the last years of Cao Cao. In this film, it is mentioned that Cao Cao built underground walls, which showed that Cao Cao was not temporary at all, but because of the long-term plan.
"The Great Wall of the Earth" offers the Cao Cao army many benefits. This work not only helps Cao Cao easily secretly transport, but also can display an ambush to the opponent. Therefore, this project has a very important military significance during the time of the Warring States.
After the Cao Cao period, many kings knew about the existence of this work. They also use it very well to gain an advantage in battles. If it was not during the Song Dynasty during the great flood, the region of Bezhou (present-day Anhui province) was submerged in water, causing the "underground city" to be completely buried, then the splendor of the tunnel This doesn't just stop there.
After losing all traces of the Southern Song flood, it was not until 1969 that people discovered the traces of this work.
At that time, the Chinese people responded to the government's call to build air defense tunnels, so the "underground wall" was only appeared once again.
Experts conducted a survey on the discovered monument and estimated that the "underground wall" was longer than 8,000m. Not only the structure of each section has different uses, but the turns are designed like a T shape.
These turns not only make the transportation of food and weapons more convenient. Moreover, just by looking at it from the outside, it would be difficult to detect those underground turns. This is as an additional proof that Cao Cao is a genius leader and always takes very cautious steps.