The astronomical observatory of Cheomseongdae has both rectangular edges and round parts with graceful carves. The round part and the rectangular part each represents the sky and the earth.

According to the records, the square window opening in the middle was the hole through which people went in and out of the observatory. Supporting this explanation are the small holes that were found inside. It’s believed that they were made by people leaning a ladder against the inner wall. This indicates that people went into the observatory through the window opening using a ladder, and then climbed up another ladder from the inside to the top, to observe stars. Below the window opening is filled with dirt and gravel, which makes a strong platform for people to stand on.

A total of 362 blocks were used to build the observatory. The number of blocks represents the number of days in a year in a lunar calendar. The 12 layers of stone blocks represent 12 months that make up a year. This suggests that the observatory might have served as a calendar for people of Silla.

This observatory was near the royal palace of Silla. An astronomical observatory needed to be close to the palace, so that any changes observed in the sky could be promptly reported to the king.

Since Cheomseongdae Observatory was built, records of observations of solar and lunar eclipses, appearance of comets and extreme weather events were made more frequently. The observations are also known to be very accurate. Cheomseongdae Observatory carries both a significant scientific value and beautiful appearance, making it a perfect example of Silla’s advanced knowledge of science and refined artistry.