Difficulty: Summiteer (Level 3)
Visitors to the Forbidden City in Beijing might find it hard to ignore its magnificent red door, but there is more to the entrance than its beauty.
The golden door nails not only line up neatly, but they were also exclusive to the royal family and cannot be seen everywhere in China.
In the Ming (1368–1644) and Qing (1644–1912) dynasties, door nails were a symbol of hierarchy and were bound by strict rules.
The number of nails had to be odd because, in traditional Chinese culture, odd numbers represent yang, or light, and even numbers represent yin, or darkness.
Nine is the largest odd number under 10, so it became exclusive to the emperor, symbolising his supreme power and divine authority.
In the Forbidden City, the gates are painted red, which is a colour of solemnity and prosperity. The major gates are adorned with 81 gilded door nails, arranged in a strict nine-by-nine grid.
