Cheomseongdae stands as a testament to the advanced astronomical knowledge of the ancient Silla Kingdom. Constructed in the 7th century, it is the oldest surviving astronomical observatory in Asia, and possibly the world. This remarkable structure was designated as South Korea's 31st national treasure and forms part of the Gyeongju Historic Areas, a UNESCO World Heritage Site. Its design, featuring 365 stones, symbolizes the days of the year, reflecting the Silla people's intricate understanding of time and the cosmos.