Central Axis
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.
中轴线
中轴线是中国传统建筑物（群）中轴对称布局的中心线，是中国传统建筑格局与城市布局的重要特征，源于古代中国人对于天地轴线的理解。中国古代重要建筑大多呈中轴对称格局，主要建筑按照一定的原则分布在中轴线及其两侧，南北层次分明，东西对称分布，布局严谨。
中轴线的建筑格局与“居中”“居北”“面南”的观念有机结合。基于这种理念，中国古代都城大多较为方正。北京中轴线是中轴线建筑格局的集大成者，有外城、内城、皇城、宫城四重城阙，故宫在最中心，形成了独特的城市建筑秩序。北京中轴线南起永定门，经天安门、午门，穿过故宫的太和殿、中和殿、保和殿，越过景山，北至钟鼓楼，全长7.8公里，是北京城的重要标志，也是世界上现存最长的城市中轴线。
中轴线是中国古代都城建筑格局的突出体现。从夏商时期的偃师、秦汉时期的长安城、汉魏时期的洛阳、隋唐时期的长安，到燕下都、金中都、元大都和明清北京城，再到1949年后的北京城建设，都是以一条轴线为中心对称的格局。中轴线体现了中华文明以中为本、以和为贵的精神，展示了中国人通过规划布局表达对政治理念、文化象征和生活空间的认识发展。
