Wat Mai is a defunct temple formerly located on Ayutthaya’s city island in Ho Rattanachai Sub-district, near an area previously called Laem Sarapha (1).
Based on a 19th-century map drafted by an unknown surveyor, the monastery was situated along the east bank of Khlong Pratu Jin (2) and south of the old road running over the Pratu Talat Jin Bridge (3). The temple stood west of Wat Sam Jin and northwest of the Ok Kai Fortress. Wat Krabue was north.
Historical data about the monastery and its construction are unknown.
The map indicates the existence of a chedi.
The temple features on no other maps of Ayutthaya.
Assessing all the monastic structures in the zone demarcated by Chikun Road, Pa Thon Road, Pridi Banomyong Road and U-Thong Road is rather complex, as the position and name of the structures vary on different maps. On a 19th-century map, there are 15 structures counted, while on the 20th-century PBR map, there are 13 mentioned. There is inconsistency in the names and the positions. Even maps drafted by the Fine Arts Department, what I presume, based on excavations in the zone, shed no light on this matter. The positions of monastic structures can be asserted, but their ancient names will remain questioned forever.
Wat Mai could have been located near geographical coordinates: 14° 20' 56.90" N, 100° 34' 13.26" E.
The location of Wat Mai coincides with or must have been very near to the residence of Ban Jao Phraya Wichayen. The question remains whether this could have been the same place.
Footnotes:
(1) Hua Sarapha is the southeastern point of Ayutthaya's city island opposite Wat Phanan Choeng. Today it is situated at the confluence of the Pa Sak River and the Chao Phraya River. Still, in the Ayutthaya era, it was at the junction of two branches of the Lopburi River, as the Lopburi River arriving at Hua Ro, encircled the city. Hua Sarapha was known as the harbour area. Hua Sarapha was more or less defined by a space between Pom Phet and Pom Ho Racha Khrue.
(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 at that time 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.
(3) On the 19th-century map, we find next to the canals, the old roads which now are gone or primarily altered. U Thong Road was constructed in 1895 CE under the Governor of Ayutthaya, Phraya Chai Wichit Sitthi Satra Maha Pathesathibodi. Most parts of the walls and the forts were dismantled in the reign of King Rama I (1782-1809 CE) and King Rama III (1824-1851 CE), and the foundations were used for the construction of the road. The map shows only remnants of the wall on the northeastern area near the Front Palace. The south road over the Sing Bridge, the Wanon Bridge and the Pratu Talat Jin Bridge no longer exists.