Chom-sung-dae of Kyongju, an astronomical observatory built in the 7th century Shilla, has never been regarded otherwise as a structure with any other purpose. Recently, however, different views have been raised about Chom-sung-dae claiming that it was "an alter" or that it was "merely a symbolic tower." It may be said that the reasons for such different theories arising on Chom-sung-dae are the result of some studies in which examination as to its functional aspect as a place of observing work was carelessly neglected while only its difference in appearence as against a modern-day observatory was solely emphasized. To be more specific, 1) Chom-sung-dae seems to have disregarded the installation of a safe and comfortable access, but this testifies all the more that its builders attached greater importance to its practical purpose. 2) It is located not in the mountains but in town limits, but this is only natural selection of a site for an observatory in ancient times when there were neither electric lights nor dusts from pollution. 3) The observing platform is at a height of about 9 meters, but this is a modest level high enough for avoiding obstruction of vision from surrounding trees. As these points are all characteristics of observatories in old times, they are quite different from those of modern observatories. So, they may sometimes look strange to men of today, and this is why there sometimes arise divergent opinions on Chom-sung-dae.