Wat Noi Wang Lang, or the Little Monastery of the Rear Palace, was located on Ayutthaya’s city island in the western area in the Pratu Chai sub-district. The monastery was situated south of Wang Lang (1) and was part of the latter. Wat Kasatra stood on the opposite bank of the Lopburi River (at present, the Chao Phraya River after its deviation to Ayutthaya in the mid-19th century). In 2012 CE, the Fine Arts Department performed excavations in the area and found evidence of what has been a temple area dating from the Ayutthaya era. Although much more east than indicated on PBR's map, the site is supposed to be Wat Noi, a temple belonging to the former palace area. During the excavations, evidence of the temple's outer wall was discovered and pieces of sandstone and bronze Buddha images, the foundations of a chedi and the pedestal of boundary stones (Bai Sema).
Maps
Although I am not sure, Wat Noi Wang Lang could show on Kaempfer’s draft map. Engelbert Kaempfer (1651-1716 CE) was a medical doctor working for the Dutch VOC (Verenigde Oost-Indische Compagnie) who surveyed Ayutthaya in June 1690 CE. On the map, there is an indication of a structure at the southeast corner of the Rear Palace premises.
Also, Jacques-Nicolas Bellin (1703-1772 CE) shows Wat Noi in the southeast corner of the Rear Palace premises on his map ‘Plan De La Ville De Siam’ published as plate No. 4 in volume 9 of the 1752 CE French edition of Abbé Antoine François Prévost's l'Histoire Générale des Voyages. He was one of the most important cartographers of the 18th century a hydrographer and 'ingénieur hydrographe' at the French 'Dépôt des cartes et plans de la Marine'. The Rear Palace is here named ‘c. Pagode ou le Roi de Siam regnant alors avoit été élevé’ meaning ‘Pagoda or the then reigning King of Siam had been raised’ referring to King Narai (reign 1656-1688).
The site is indicated on a mid-19th century map drafted by an unknown surveyor. Wat Noi Wang lang is situated south of Wat Suan Luang and in the front of the boat landing called ‘Dan Lom’. The map indicates the existence of two chedis.
The temple appears on Phraya Boran Ratchathanin's map drafted in 1926 CE as Wat Noi and seems to be part of the Rear Palace. Phraya Boran (1871-1936 CE) was the Superintendent Commissioner of Monthon Ayutthaya from 1925 till 1929 CE.
Historical data about the monastery and its construction are unknown.
The site is in geographical coordinates: 14° 20' 57.31" N, 100° 32' 53.29" E.
Footnotes:
(1) Wang Lang or the Rear Palace is a defunct palace of the Ayutthayan era, earlier situated on the premises where now the Fine Arts Department (FAD) - Region 3 is located, adjacent to Chedi Phra Si Suriyothai, part of Wat Suan Luang. The area was in the 20th century a liquor distillery.