Located in the Grand Palace compound, the largest temple in Ayutthaya. This Royal Palace was built by King U-Thong upon the founding of the city. Used as a residential palace, it became a monastery in the reign of King Ramathibodi I. When King Borom Trai Lokanat commanded the construction of new living quarters, this residential palace was transformed into a temple, and the establishment of Wat Phra Si Sanphet. The three main chedis which have been restored contain the ashes of three Ayutthaya kings. The royal chapel does not have any monks and novice inhabitants.