Abstract
About 300 years ago in Lopburi and Ayudhaya, many astronomical observatories were designed, constructed, and supported by the Roman Catholic missionaries from Europe and by King Narai the Great of Siam (Thailand). The interesting recorded history of Thai astronomy was found in the national museum of France a few years ago. Afterwards, the ruined observatories were searched for and found. A tercentennial commemorative ceremony of Thai astronomy was held on April 30, 1988.
