Wat Mahathat (fig.) in Ayutthaya was the residence of the patriarch of the Buddhist church in the Ayutthaya Period, and its name refers to the fact that it houses a relic of the Buddha.

It is located to the East of the former Grand Palace and as a royal temple, it had the Buddha's relics enshrined in the principal pagoda.

According to the Royal Chronicle the monastery was built in the reign of King Boromarachathirat I and completed in the reign of King Ramesuan.