Why is Ganling the most difficult tomb to dig? What kind of mechanism does it hide?

Ganling is a treasure trove of geomantic omen discovered by two famous warlocks Yuan Tiangang and Li in Tang Dynasty. It was built under the auspices of Wu Zetian, who is a very clever person. With the help of Yuan Tiangang and Li, many organs must be used to build Ganling. So far, no one has been able to really see the organs inside, so Ganling is called the ninth wonder of the world.

I. Location When Wu Zetian was in office, she always sent someone to look for a treasure trove of geomantic omen as her and Tang Gaozong's mausoleum, but she couldn't find it. Later, she sent Feng Shui master Yuan Tiangang and fortune teller Li to look for it. Yuan Tiangang couldn't find it at first, until one night, Yuan Tiangang came across a mountain with purple gas coming out. Yuan Tiangang was afraid that he couldn't find it the next day, so he took out copper coins and made a mark.

Later, Li also went there and saw the direction of the mountains and rivers like a naked woman. Li thinks the moral is very good, just like the birth of the queen, which implies Wu Zetian. So he took a needle and marked it. When I went back to reply to Wu Zetian, Wu Zetian found that the two said the same thing, so she sent someone to dig and found that Li's needle was inserted in Yuan Tiangang's copper coin. Wu Zetian was overjoyed and immediately decided to build a mausoleum here, namely Liangshan, Xianyang City.

Second, why is Ganling the most difficult grave to dig? Because the tomb robbers in many dynasties have not found the entrance to the tomb so far, the tombs of emperors in previous dynasties are the most easily looted by tomb robbers, because the funerary objects of emperors are relatively valuable, especially the tomb of Wu Zetian, where two kings are buried. According to historical records, there are countless gold, silver and jewels buried with him.

However, after the completion of Wu Zetian, the auxiliary tombs of Yuan Tiangang and Li were impressive. So many grave robbers thought about it, but none of them could find the entrance, let alone what the organs inside were like, because no one had been there, and everyone's understanding of Ganling was limited to books, which showed the wisdom of the ancients.