Tian'anmen Gate stands directly in the center of Beijing. An imaginary axis line, 7.8 kilometers long, begins in the south at Yongdingmen Gate (no longer extant) in the former outer city wall; further north, it passes through Zhengyangmen Gate (South-Facing gate, popularly known as Qianmen or Front Gate), Tian'anmen Gate and Duanmen Gate (which stand before the Imperial Palace), and Wumen Gate, the southernmost entrance to the palace proper. From there, it continues north through its northernmost gate, Shenwumen (Gate of Giving Prowess). It then passes through Longevity Pavilion (Wanshouting) atop Prospect Hill (Jingshan) and ends at the Drum and Bell Towers.

This axis splits the city into approximate halves, each of which was built in Ming times with symmetrically arranged pairs of gates. Although the gates have been torn down to make way for modern roadways, their names are still used to designate city districts: for example, Dongzhimen and Xizhimen, Fuchengmen and Chaoyangmen, and Xuanwumen and Chongwenmen. It is curious to note that the central axis passing through Tian'anmen lies approximately 200 meters east of the true axis of symmetry as calculated from the distance between the city walls.

With the exception of the Imperial Palace, nearly all the structures built in and around Tian'anmen Square after the founding of the People's Republic of China in 1949. During the Ming and Qing dynasties, gates with three openings each stood at the southern, eastern and western extremes of a narrow plaza south of Tian'anmen Gate.

In the Ming Dynasty, a roofed walkway called the "Thousand Bu Corridor" was built within this plaza. Bu means both "footstep" and a distance equal to approximately five feet.

During the Ming and Qing dynasties, the principal organs of the Chinese government established their offices on either side of the walkway. To the east were the Ministries of Ceremonies, Finance, War, Works, Personnel, Meteorology and Astronomy. To the west, during the Ming Period, were the Bureau of Embroidered Robes (Jinyiwei), which supervised espionage activities, and the five chief military commissions. In the Qing, the Ministry of Punishments, the Censorate and the Taichangsi (an office responsible for ceremonies and sacrifices) were located here. The whole area in those days was crowded with luxuriantly dressed officials and fine palanquins.

In 1949 the square was greatly expanded, taking on an entirely new aspect. It was here, on October 1, 1949 that Mao Zedong, speaking before a crowed of 300,000, proclaimed the founding of the People's Republic of China, and raised for the first time the Chinese national flag. Ever since, a large portrait of Mao Zedong has hung over the central archway of Tian'anmen Gate. The large plaques to each side read, "Long Live the People's Republic of China "and "Long Live the Unity of the Peoples of the world."