The round nail on the Forbidden City in Beijing actually has another function, that is, fire prevention, because the doornail was actually made of wood at first, and later it became iron, and copper was used to prevent fire. In the Ming and Qing dynasties, many giants also used this kind of nail, which also symbolized the atmosphere of giants. With this kind of door nail, the door looks not monotonous, but also beautifies the decoration of the door. The nails used in the gate of the Forbidden City are different from other ordinary nails, and the number of nails in the Forbidden City is also different. How much to use in each row and how much to use in each vertical direction are all particular.
Generally, how many nails will embody a supreme person and the supremacy of imperial power. The nails in front of the emperor must be different from those of other princes and others, because the number and arrangement of their doornails are different in different positions and grades. Ordinary people don't need nails at all, and only those nobles can use them. If there is an opportunity, I also want to visit the Forbidden City. I also want to carefully observe how many nails there are in front of the Forbidden City. I also want to touch them, but I seem to hear that I can't touch them.
So the rows of round nails in front of the Forbidden City in Beijing are actually very symbolic and represent an authority.