The pit at the center of Phra Chedi Chai Mongkhon is the spiritual heart of the pagoda, serving several historical and religious purposes:

• The Relic Chamber (Kru): Traditionally, this pit served as a "Kru" or treasury to enshrine Lord Buddha's relics and valuable artifacts as offerings during the pagoda's construction.

• Source of the Victory Chant: It is believed that the Chaiya Mongkhon Katha (Phahung Prayer)—the prayer of victory given to King Naresuan by the Abbot of Wat Pa Kaew—was discovered or originated from this sacred site.

• Coin Tossing Tradition: Today, many visitors toss coins into the pit for merit-making and divination. It is a popular belief that if your coin lands in the center, your prayers for success will be granted.