Queen Sandok-yowang (632-646 A.D.) of the Shilla kingdom built Cheomseongdae Observatory in 646. This is believed to be one of the oldest observatories in the world. In the bottom there are 12 stones in a circle and the observatory is made of 366 stones. Twenty-seven layers of square hewn granite stone were built up to form a cylindrical, bottle-shaped tower on a square base. The top square has the 4 sides pointing north, south, east or west, and is believed to have aided astronomical observations. There is a square opening facing due south between the 13th and 15th layers of the granite stones. The hole is the old entrance, and it points south. The observatory is 5.17 meters in diameter and 9.4 meters in overall height. This is one of the best preserved of Shilla relics. It is believed to be a kind of observatory to time the astronomical sunrise, noon, sunset, etc, and also believed to be used for astronomical observations putting astronomical instruments on the roof of Chomsongdae. The direction, size and angles of its windows were designed such that they could observe correct time for 24 sub-seasons. A local guide, Sang-sub Song who we are in great debt to, has taken the photo. He used 1 ½ day showing us around in the area and mountains close to Kyongju.