Like overseas sanctuaries and the pyramids in ancient Egypt, theForbidden CityinBeijingenjoys a set of rules governing the choice of architectural dimensions. Fu Xinian, an architectural historiographer, tried to decipher the mystery of numbers by carefully measuring the area of every courtyard and the exact location of individual places within the complex.

 The Forbidden City: the Mystery of Numbers

With careful examination, Fu Xinian concluded that the layout of individual courtyards in the Forbidden City was designed according to a certain ratio.

Fu started with the courtyard in the rear composed of 2 residential dwellings of emperors and concubines, and the courtyard in the front consisting of 3 grand halls where emperors handled official businesses.

According to his measurement, the rear courtyard is 218 meters long and 118 meters wide, and the front courtyard is 437 meters long and 234 meters wide. As a result, the ratios of the length to the width in both courtyards turn out to be the same, reaching 6 to 11, and the courtyard in the front is twice as long and wide as the rear courtyard, which consequently means the front courtyard is 4 times the size of the rear one.

Another example is the structure of the Hall of Supreme Harmony (Taihe Dian), which displays overwhelming imperial power. It was designed according to the 9-by-5 standard. There are 9 bays (literally rooms that are each enclosed by 4 poles) in length and 5 bays in width. Therefore, the ratio of its length and width reaches 9 to 5.

Both 9 and 5 carried special meanings in ancientChinese architecture. Numbers can be divided into odds and evens, which fall into the categories of Yang and Yin respectively according to the Yin-Yang principle (concerning opposing elements). Within the odds less than 10, 9 is the largest one and 5 ranks in the middle. Accordingly, both 9 and 5 connoted the supreme imperial power in ancient China.

 Why are there some exceptions?

Tourists may find that there are 11 instead of 9 bays in length in today's Hall of Supreme Harmony. The reason lies in the fact that the original Hall of Supreme Harmony was destroyed by the end ofMing Dynasty(1368-1644) and repaired in 1669 under the reign of the EmperorKangxiin theQing Dynasty(1644-1911). Due to the lack of a specific special superior wood during the restoration, the width was adjusted to 11 bays.