Wat Kaeo, or the Crystal Monastery, is a defunct temple located on Ayutthaya's city island outside the Historical Park in the Pratu Chai Sub-district.
The monastery features curiously enough not on Phraya Boran Rachathanin's map drafted in 1926 CE but is indicated on a 19th-century map by an unknown surveyor. (1)
On the latter, Wat Kaeo stood south of Wat Mae Nang Muk on the west bank of Khlong Pratu Jin (2) and more or less opposite Wat Khok Suea (defunct) and Wat Khok Saeng (defunct). The 19th-century map indicates no existence of a chedi nor prang.
The monastery's historical background and period of construction are unknown.
There are discrepancies between the 19th-century map and Phraya Boran Rachathanin's map regarding the area west of Khlong Pratu Jin.
On the oldest map, Wat Chatthan is situated north of Pa Thon Road instead of south. Wat Chatthan is here in line with Wat Song Khon.
Wat Noi Nang Muk is situated at the southwest corner created by Khlong Pratu Jin and Pa Thon Road (Chikun Bridge) and is positioned on the 19th-century map in the location where today is believed Wat Chatthan stood. The oldest map shows the presence of a chedi, while the remaining brickwork of Wat Mae Nang Muk is a prang.
The position of today's Wat Mae Nang Muk is on the oldest map Wat Kaeo. On the other hand, Wat Kaeo is shown without a chedi or prang.
In conclusion, Wat Mae Nang Muk could have been yesterday's Wat Kaeo.
Footnotes:
(1) Phraya Boran Rachathanin’s map indicates a monastery with a similar name in the area of the old Rear Palace, as well in the Somdet Phra Sri Nakharin Park.
(2) Khlong Pratu Jin, or the Canal of the Chinese Gate, is part of a waterway running through the middle of Ayutthaya from north to south. The canal ran from the Chikun Bridge to the Chinese water gate (Pratu Jin) one of the eleven water gates and was an extension of Khlong Pratu Khao Pluak. The canal was a shortcut through the oxbow of the Lopburi River and connected the old Lopburi River, present Khlong Mueang in the north with - what is today - the Chao Phraya River in the south. The canal could have been the eastern defence moat of the initial city.
