Tianzhong Mountain, also known as Tiantai Mountain, lies two kilometres north of Runan County seat. It covers an area of about 540 square metres with a height of only 3.6 metres. It got its name from the stone tablet inscribed with three Chinese characters "Tianzhong Mountain" handwritten by Yan Zhenqing.

Brief Introduction Tianzhong Mountain, formerly a round mound, covers approximately 540 square metres and stands 3.6 metres tall, two kilometres north of downtown Runan.

Historical records state: "Emperor Yu divided the realm into nine provinces. Yuzhou lay at the centre of the nine provinces, and Runan sat right in the heart of Yuzhou. Hence this place is called the Centre of Heaven."

There is another version of the origin. In ancient times, there were no water clocks, and time was measured solely by the movement of sunlight shadows. Old local chronicles of Runan record: "Since ancient times, this site has been the benchmark for measuring solar shadows. Mounds of earth and stones were piled up to mark this geographical midpoint."

That is why Runan is hailed as the Centre of Heaven.

A folk ballad has long been popular among local people: "Tianzhong Hill stands three chi three high; Stand on Tianzhong Hill, one step reaches the sky."

Though exaggerated, the line captures its unique charm. "Three chi three" vividly describes how tiny the mound is, while the phrase "reach the sky" reflects the ancient belief that this place communicates with heaven and earth. Strictly speaking, Tianzhong Mountain is not a real mountain. It is merely a geographical landmark, a cultural symbol, and even a totem.

The Centre of Heaven refers to present-day Runan County, Zhumadian City, Henan Province. According to Tribute of Yu: "Yu divided the country into nine provinces. Yuzhou was the middle of the nine provinces, and Runan was the centre of Yuzhou, so it became the Centre of Heaven."

Legend says that Tianzhong Mountain and the old Runan city were arranged in the shape of the Big Dipper. The northern city gate was named Beigong, meaning "guarding the empire". This layout laid the foundation for the north-south central axis in ancient Chinese urban planning, yet the north and south gates of Runan City are not aligned on a straight line.

Owing to its unique geographical location, King Wu of Zhou ordered a mound to be built here as Tianzhong Mountain. A sundial gnomon was erected on top to take accurate measurements of solar shadows.

The stone inscription of "Tianzhong Mountain" written personally by the great calligrapher Yan Zhenqing of the Tang Dynasty is still preserved today. After climbing Tianzhong Mountain and visiting Nanhai Temple, the renowned poet Liu Yuxi composed the immortal verse: "A mountain need not be high; it is famous so long as there is a fairy on it. A lake need not be deep; it gains magic power as long as a dragon dwells within." These lines perfectly depict the spiritual aura and wonder of this sacred land.

In recent years, the county government has invested heavily in public recreational facilities. As a key project, Tianzhong Mountain has been developed into the largest leisure and entertainment park in Runan County, officially named Tianzhong Mountain Ecological Park.