As we all know, the rural water tank is one of the folk elements, almost every family will have a large water tank in the yard, in the summer, there are dragonflies flying to some water, before sunset, there will be sparrows flying to wash feathers on the rim of the cylinder. Of course, the water tank is not placed randomly, and there is a saying: the hidden wind gathers gas, and the water is the best. Some feng shui practitioners believe that when the natural conditions around the house cannot meet the "mountains and waters", they will build rockeries and place fish tanks in the courtyard.

However, if compared with the Forbidden City, the water tanks of ordinary people are not worth mentioning, because at the entrance of the three halls of the Forbidden City, as well as on both sides of the Taihe Hall, there are several large water tanks with "golden sparkle".
In fact, the large water tank placed in the courtyard has an exclusive name - Menhai. The so-called "door sea" is the sea in front of the door, and the ancients believed that the door sea has both the role of avoiding evil and the role of extinguishing fires. Most of the ancient Chinese houses are wooden structures, once encountered in the fire, if not extinguished in time, it is likely to cause a big fire, and it is too late to go to the well to get water. As a result, the role of the Gate Sea was highlighted, and in the Forbidden City, which occupies a huge area, the Gate Sea became an indispensable thing, because in history, the Forbidden City did have several fires.
In 1421 (the nineteenth year of Yongle), the Forbidden City burst into flames, and the first three halls were burned; in 1557 (the thirty-sixth year of Jiajing), the first three halls of the Forbidden City, Fengtian Gate, Wenwu Tower, and Noon Gate were burned down... Finally, coupled with the natural disasters and man-made arson in 1597, 1644 and 1923, the Forbidden City was burned a total of 5 times before and after, if it were not for the help of the door and the sea, I am afraid that this fire was not so easy to control, after all, there was no modern fire fighting equipment at that time, once it spread to other halls, perhaps future generations would not see the majestic and brilliant Forbidden City.
However, how many mouths and seas does the Forbidden City have? 308, which is the total number, including both those displayed in front of the door and those placed in the courtyard. Of course, the placement is different, the manufacturing process and materials of the door sea are also different, the so-called "façade is the face", if it is perfunctory, it may be laughed at by the people of the world. Unfortunately, there are only 231 gate seas left today, of which there are 18 gilded golden gate seas, and the rest are bronze gate seas or black iron gate seas, whether ornamental or valuable, can not be compared with gilded golden gate seas.
It is worth mentioning that the origin of this gilded golden gate sea is also related to the great corrupt officials and the emperor. He Yan and the Qianlong Emperor were a natural match, a flattery, a good great achievement, although Qianlong wrote more than 50,000 poems in his lifetime, but only one was passed down to future generations, which shows how far his "good face" has reached. Therefore, Qianlong ordered Hezhen to create 22 pure Golden Gate Seas to show the prestige of the royal family. However, He Yan was notoriously greedy, and even at Qianlong's order, he was yang and yin. In this way, the pure Golden Gate Sea became the Gilded Gate Sea, and the Washu was only plated with a layer of gold on the outside, and the internal material was still bronze.
In 1900, the Eight-Nation Alliance invaded Beijing, and Empress Dowager Cixi fled in a hurry, not only the entire Forbidden City was looted, but even the Gilded Gate Sea was "brutally killed." Finally, the gold on the surface of the Gilded Gate Sea was scraped off by the Eight-Nation Alliance, of which 4 were also lost in the war, and the 18 Gilded Gate Sea that remained still had deep scratches on the surface, which were both witnesses of history and reminded future generations at all times: Do not forget the national shame.