Cheomseongdae (첨성대) (Gyeongju)

 observatory, listed building / architectural heritage, historic landmark

Cheomseongdae, meaning star-gazing platform in Korean, is an ancient astronomical observatory in Gyeongju. Cheomseongdae, the oldest surviving observatory in East Asia, was constructed durring the reign of Queen Seondeok (632-647) and is one of the oldest scientific installations on Earth.

Cheomseongdae dates to the 7th century to the time of kingdom of Silla, which had its capital in Gyeongju. The tower is built out of 362 pieces of cut granite which some claim represent the 362 days of the lunar year. It has 27 circular layers of stones surmounted by a square structure. 12 of the layers are below the window level and 12 are above. There are 12 large base stones set in a square, with three stones on each side. These sets of 12 may symbolize the months of the year. The tower is 5.7 meters/18.7 feet wide at the base and 9.4 meters/30.8 feet tall, and filled with earth up to the level of the window

Cheomseongdae was designated as the country's 31st national treasure on December 20, 1962.