Ancient Observatory of Korea

Stars of Orion and Canis Major (with Sirius, just above the monument) pass in the sky of southeastern Korea. The foreground monument, a tower of about 9 meters tall, is known as the oldest remaining observatory in East Asia. Named Cheomseongdae, it dates to the 7th century at the time of kingdom of Silla. On top of the tower there are four stones, facing exactly the four cardinal points. Total numbers of stones are 361, which is equal to the days of one lunar calendar year. The tower is piled up with 28 steps of stones, which represents Oriental basic of 28 constellations. In the middle of observatory, there is a window, facing exactly south. At the summer solstice, the sunlight which passes the window fully reflects on the floor. While at the winter solstice, the sunlight which passes the window is completely vanished from the floor.