Wat Yai Chai Mongkhon or the Great Monastery of Auspicious Victory is located
off the city island in the southeastern area of Ayutthaya in present Phai Ling Sub-district.
In the past it bears other names as Wat Pa Kaeo, Wat Chao Phraya Thai and Wat Yai
Chaiya Mongkhon.
The easiest way to reach this active monastery is by turning south at the roundabout
chedi on Rojana Road (Wat Sam Plum) along road No 3059. The temple can be easily
found at the eastern side of the road. Wat Yai Chai Mongkhon is situated in a part of the
ancient city known as Ayodhya. It is widely believed that a Dvaravati (and Lopburi
allied) settlement existed here before King U-Thong established Ayutthaya in 1351.
There are indications that the site was surrounded by a large moat in earlier times. The
monastery was accessed before by Khlong (Pak) Khao San, which got its mouth at the
new Pa Sak River. There are also traces of an ancient canal east and west of the temple;
the latter ran, parallel with Khlong Khao San, also towards the Pa Sak River.
There are seemingly traces from an ancient baray or water reservoir, close to the
southwestern tip of the monastery. It could thus be that Wat Yai Chai Mongkhon has
been built on a former important Khmer temple complex - taken also in account the large
moat which represented for the Khmer, the oceans that surround the world. (1)