Wat Rang, or the deserted monastery, is located off the main island, on the western side of the Ayutthaya in the Pak Kran Sub-district. The site is just east of Wat Krachai. Wat Tao and Wat Ta Muk stood north.
It can be found inside a small bush surrounded by rice fields in the bend of Road No 3469.
There is a brick mound with likely remnants of a monastic structure. Pieces of Buddha images can be seen scattered around the site, as well as many red bricks.
The 2007 CE Fine Arts Department map shows three excavated structures on the map. These structures could belong to the nearby Wat Krachai and were maybe not part of a separate temple. It remains though a guess.
The historical background and construction period of the former monastery are unknown, although the temple is mentioned in the Royal Chronicles of Ayutthaya.
The army of the Burmese General Nemiao Sihabodi (Ne Myo Thihapate) set up army camps around the city of Ayutthaya in early 1767 CE. One of the enclosures reinforced with bastions was set up at Wat Krachai. From this position, the city was fired at with large guns.
"The next morning Nemiao, the general of the armies, conscripted men and had all his army masters and brigade masters lead them on in to establish stockades at the Monastery of the Krachai Plant, the Monastery of the Victory Pavilion, the Monastery of the Tortoise, the Monastery of the God Indra and the Monastery of Red. They had bastions built in each and every stockade and large and small guns taken up onto them to be fired at the capital in volleys.” [1] (Named respectively: Wat Krachai, Wat Ta Muk, Wat Tao, Wat Suren and Wat Daeng)
Wat Rang is in geographical coordinates: 14° 19' 58.13" N, 100° 32' 15.39" E.
References:
[1] Cushman, Richard D. & Wyatt, David K. (2006). The Royal Chronicles of Ayutthaya. Bangkok: The Siam Society. p. 512.