Prior to the construction of the Forbidden City, there was no water and hill in the palace originally and the then emperor 明永乐皇帝 decided to create water and hill in the palace. Thus, he ordered his men to create a hill at the back of the palace which is at the North, called 万岁山（后改名为景山）. Water was brought in from the North West of the palace which according to the theory of the later heaven bagua is the sector of the King or Master 乾 (Qian) or heaven 天. The water flows from the North West to South East of the palace. South East is the sector of wind 巽. It means the water is the rain from the sky (heaven) and evaporates as air (wind).
The formation of hill and water in the Forbidden City is according to the theory of front red phoenix and back lack turtle 前朱雀后玄武. There is a support at the back and in front of the palace is ample of space which means bright hall 明堂.
The river in the Forbidden City is called the Golden Water River 金水河 and the flow the river is bent and curved and it is auspicious as if the flow of the river is bent and curved then it is passionate. Whereas, straight flow of water is ruthless instead.
The shape of the Golden Water River 金水河in front of the Hall of the Supreme Harmony (the main hall in the Forbidden City) 太和殿 is known as the 玉带环抱 ‘yu dai huan bao’ a jade belt around your waist. It is like someone is hugging and protecting you. Jade belt was a belt worn by ranking officials in the old China. Hence, if you have a house located at the auspicious sector then your relationship with family members and people around you will be remarkable and your luck in terms of wealth will be excellent. However, if your house is located at the opposite side, then it is defined as 反弓水 bend bow water, which is an inauspicious location, then your luck in terms of wealth and relationship with others will not be prosperous.
明永乐皇帝定京师于北京,按风水营建紫禁城,原来没有金水河和万岁山（后改名为景山），基于风水格局之考虑，无天然河水就要风水工力改造，成“背山面水”之格局。紫禁城正北也就是后方设有玄武门（后改名为神武门），其后需建山为屏障增靠山。这也是我们所说的左青龙右白虎前朱雀后玄武. 前面是一片大广场为好的明堂. 后面是靠山.