Cheomseongdae (Chomsongdae) is a 7th-century CE observatory tower located in Gyeongju, the capital of the Silla Kingdom of ancient Korea. It is the oldest surviving astronomical observatory in East Asia and is listed as no. 31 on the official list of National Treasures of Korea.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Cheomseongdae/.