The central axis determines the symmetrical layout of traditional Chinese buildings. An important feature of traditional Chinese architectural and urban layout, it originated from the ancient Chinese understanding of the axis of the heavens and the earth. Most of the important groups of buildings in ancient China had a symmetrical layout along a central axis, with the main buildings constructed along the axis or on its two sides. The buildings follow a rigorous layout, with clearly-divided sections from the north to the south, and symmetrical distribu- tion on the eastern and western sides.

The architectural layout based on the central axis is cou- pled with the preference for being in the center and facing the south with the back of the building to the north. Because of such preferences, most ancient Chinese capitals were relatively square. The Central Axis of Beijing is the epitome of this architectural layout; it organizes the four layers of the city-the outer city, the inner city, the imperial city, and the imperial palaces, which form a unique urban architectural order. The imperial palaces, also known as the Forbidden City, occupy the very center of the city. The axis is 7.8 kilometers long, starting in the south of the city from the Yongding Gate, running across the Tian'anmen Rostrum, the Meridian Gate, the Forbidden City, and the Jingshan Hill, and ending with the Drum Tower and Bell Tower in the north. It is an important symbol of Beijing and the longest surviving urban central axis in the world.

The central axis is a prominent feature of the architectural layout of ancient Chinese capitals. The construction of the cap- ital was based on a central axis from the earliest Xia and Shang dynasties all the way to the Ming and Qing dynasties. After the founding of the People's Republic of China in 1949, the construction of Beijing continued to follow this symmetrical layout. The central axis embodies Chinese civilization's emphasis on the doctrine of the mean and the pursuit of harmony, and demonstrates the Chinese understanding of politics, culture, and living spaces.