Wat Sanam Chai, or the Monastery of the Field of Victory, is an active temple located off the city island in the western area of Ayutthaya, in the Ban Pom Sub-district. Wat Chai Watthanaram (restored ruin) is north, while Wat Kuti (mound) is south.
The monastery features an ordination hall with a single porch supported by four pillars. It has a double-tiered roof. The porch also has a second lower double-tiered roof, while to keep the visual balance, the west side of the ubosot, though not having a porch, was lowered with a double-tiered roof. Some Chinese ceramic ware decorates the front gable. There are two entry doors on the east side, and the sidewalls have three windows. A low wall surrounds the hall.
Behind the ubosot, but a bit southward, there is a four-tiered pyramidal square chedi, built of brick and mortar, reflecting the Mon style. A small bell-shaped dome tops the structure. The stupa is hollow inside and contains old Buddha images in perfect condition.
On Simon de La Loubère's map of 1693 CE, it is indicated that 'Peguans' (Mons) settled in the area between Khlong Takhian (1) and Khlong Klaep (2).
Wat Sanam Chai was likely a temple of the Mon community in the late Ayutthaya period.
Based on the Temple Registration System of the National Office of Buddhism, Wat Phra Ngam was established around 1557 CE in the reign of King Chakkraphat (1548-1569 CE). It is thus an Ayutthaya-era temple. It received its Wisung Kham Sima in 1567 CE.
Wat Sanam Chai does not figure in the Royal Chronicles of Ayutthaya.
The history of this temple is unknown.
The site is in geographical coordinates: 14° 20' 29.92" N, 100° 32' 36.66" E.