Under the threshold of the main building of Bisezhai Station, there is a stone step with the mark of BM149 carved on it, followed by a pattern carved by the French engineer Nivel Laissez. According to the testimony of Chinese and French astronomers, this is the earliest Tropic of Cancer measurement marker on earth. From here, the Tropic of Cancer has passed through 15 countries and regions in Yunnan Province, including Shuangjiang, Mojiang, Gebishi, Mengzi and Xichu counties or cities. The Tropic of Cancer is the northernmost boundary of the sun's rays on Earth, and every year, at noon on the day of the summer solstice, people cannot see their own shadows when standing under the sun's rays, resulting in the astronomical phenomenon of "no shadow on the pole". The Yunnan Astronomical Observatory of the Chinese Academy of Sciences named Bisezhai as the "Tropic of Cancer Coordinate Point, E: 103°2′38″; N: 23°27′5″.

According to folklore, young couples will have twins’ babies when they absorb the yin and yang energy at the Tropic of Cancer, where the sun turns around. Many newlyweds stand on this Tropic of Cancer marker, facing each other, hands clasped together for 99 seconds, they will be able to live together forever, love each other forever, and the chance of having a dragon and phoenix baby or twins. And the Yunnan-Vietnam railroad also means a hundred years of good cooperation; admirers come incessantly, becoming beautiful scenery.