Also known as "Phra Thinang Yen," this royal residence was built during the reign of King Narai the Great in the middle of Thale Chup Son. The structure is a European-style single-story building, notably serving as a private observatory for the King. It was here that King Narai joined French Jesuit priests to observe lunar and solar eclipses using telescopes. This site stands as vital evidence of the adoption of Western science and the beginning of modern astronomy in Thailand. Today, it remains situated in a peaceful environment, reflecting the past glory of international relations and scientific pursuit.