Why is the Forbidden City, the first of the five historical palaces in the world, missing a corner?

Everyone must be familiar with the Forbidden City. Pictures of the Forbidden City often appear in costume TV dramas. As the capital of Ming and Qing dynasties, there are more than twenty emperors living in the Forbidden City. The Forbidden City is also very famous in the world, known as the first of the five most historic palaces in the world. But the Forbidden City is not perfect. One of its angles is not a right angle but an angle.

Some people on the internet say that it is because of Feng Shui that a corner is missing. Some people even say that it has something to do with immortals, which is really mysterious. How can so many immortals be so nosy? I think it's all fraud. The real reason should be related to topography and geology, not Machamp's confusion.

It is said that when the Forbidden City was first built, it was square and didn't lack a corner. Later, the wall in a corner of the Forbidden City always collapsed and was repaired several times. Later, professionals said there was a fault or something under it, so the emperor ordered the Forbidden City to be built into a corner.

Although the shape of the Forbidden City will be irregular, it is not a bad thing in my opinion. Some things are better if they are a little flawed, and too perfect is not necessarily a good thing.