Why do you want to use 28 pillars in the Temple of Heaven?

The inner and outer walls of the Temple of Heaven are round in the south and round in the north, and the inner wall of the dome is round and the outer wall is square, all symbolizing the circle; The top of the three-tier altar is "September 19th", the second floor is "March 5th", the third floor is "March 7th", and the sum of the three floors is 45, which means "the honor of September 5th". The circular stone in the center of the first altar is called Tianxin stone, and the surrounding fan-shaped stone has nine circles. The first lap is nine, and the second lap is eighteen, increasing in multiples of nine until ninth circle. The second altar is also nine circles, from 10 to 18, and the third circle from 19 to 27, all of which increase in multiples of nine, with nine as an extreme positive number and nine as the maximum to emphasize the sublimity of heaven.

The hall of the Hall of Prayer for the Year is nine feet, nine inches and nine minutes high. It is supported by 28 giant columns and divided into three circles. The inner circle is four Longjing columns, and the four spaces separated represent the four seasons of the year. The second circle is 12 gold column, and the separated spaces represent twelve months of a year. Twelve columns and twelve partitions represent the twenty-four solar terms of a year, and the outermost circle is separated by twelve eaves columns.