In the early periods, Prang Khaek was used as a site for Hindu rituals to worship supreme deities according to ancient Brahmin beliefs. The interior of the towers once housed sacred idols or Shiva Lingams, where Brahmins performed holy water ceremonies and chanted for the city's prosperity. Later, during the reign of King Narai the Great, areas such as Wat San Paulo were used for Christian religious rites by French priests. Mass and prayers were conducted alongside the use of the space for astronomical observations, reflecting the acceptance of diverse beliefs. These rituals were not only about faith but also part of international diplomacy and the demonstration of the royal court's power at that time.