Wat Prasat, or the Monastery of the Castle, was located in the north-eastern area of Ayutthaya’s city island in the Hua Ro Sub-district.

It was situated south of Wat Khwang and on the north bank of Khlong Pratu Ho Rattana Chai, near the Ho Rattana Chai Gate. (1)

The temple area has a classical outfit, quite large and well kept. The monastic buildings are on a typical east-west alignment. Each of these buildings has its proper inner wall and is beautifully decorated. The ordination hall has a three-tiered roof, while the main vihara has a two-tiered one. The latter contains a Buddha image of Wat Khwang, a former monastery northwest of this temple. There is no stupa on the premises.

Hengpujaroen wrote that according to some old documents, the walls around the Chan Kasem Palace or Front Palace had a length of 50 Sen (2) or approximately 2000 m. The palace occupied thus an area roughly going from the Unmilled Rice Fort (Pom Khao Phluak) and Wat Tha Sai towards the Maha Chai Fort going down to the Ho Rattana Chai Gate and running back along the Ho Rattana Chai canal towards the Unmilled Rice Gate. The palace area should have included at least eight monasteries, one of them was Wat Prasat. The issue of such significant palace ground, as mentioned here, was although heavily discussed by scholars and rejected. [1]

Wat Prasat was established in the Rattanakosin era. The monastery thus cannot have been part of the palace grounds. [2]


Wat Prasat does not show on Kaempfer’s map, which does indicate Wat Khwang. Engelbert Kaempfer (1651-1716 CE) was a medical doctor working for the Dutch VOC (Verenigde Oost-Indische Compagnie) who surveyed the city of Ayutthaya in June 1690 CE.

On a mid-19th century map of an unknown surveyor, the monastery stands along the north bank of the Pratu Ho Rattana Chai Canal, northeast of the Wat Khwang Fort. Wat Khwang stood in the east, outside the city wall and south of the Wat Khwang Fort. Wat Rong Ma stood in the south on the other side of the canal. Wat Prasat is not indicated with a stupa.

Phraya Boran Rachathanin's map of 1926 CE has Wat Prasat on the north bank of the Ho Rattana Chai Canal and the west bank of the Front city Canal. The monastery stood southeast of Wat Khwang. Wat Rong Ma was in the southwest.

At present, the temple is still active and can be accessed via the U Thong Road.

Wat Prasat is in geographical coordinates: 14° 21' 47.03" N, 100° 34' 43.07" E.


(1) Khlong Pratu Ho Rattana Chai (Gate of the Tower of the Victory Jewel Canal) was a canal with its origin near the water-gate called Pratu Khao Plueak and had its mouth at the watergate called Pratu Ho Rattana Chai. The canal linked the Lopburi River (present Khlong Mueang) with the Ku Khue Na (Front city canal). The canal was filled up in earlier years, and only a tiny stretch exists south of Wat Prasat.
(2) Sen is a traditional Thai unit of length equal to 40 m.


[1] Hengpujaroen, Nantana (2003). The study of Chantharakasem Palace for developing the Management Plan. Bangkok: Silpakorn Fine Arts University.

[2] Facebook post of Achirawich Antapant (Temple and Archaeological Conservation Club of Ayutthaya) dated 7 August 2021. There is a record of a visit of N. Na Pak Nam to Wat Prasat on 20 February 1967. He concluded the temple was established in the Rattanakosin period and thus dates from the post-Ayutthaya era. He found a boundary stone of the early Ayutthaya period. I presume the Bai Sema must have been from Wat Khwang as Wat Prasat also recuperated a Buddha image of the latter monastery.