Phra Thinang Kraisorn Siharat is a historic observatory, also known as Sanam Chan Palace, used for studying a significant total lunar eclipse during the Ayutthaya period. King Narai the Great observed the stars through a telescope alongside French astronomers to calculate global coordinates. This site was chosen for its lakeside location and open layout, providing a clear and unobstructed view of the night sky. The event was recorded as global evidence marking the dawn of modern astronomical science in Thailand. Today, it remains a vital educational site reflecting the progressive vision and adoption of Western sciences by Thai ancestors.