Wat Jan, or the Monastery of the Moon, is located on the city island in the Tha Wasukri Sub-district. The site is situated in Bueng Phra Ram Public Park, part of the Ayutthaya Historical Park.
The defunct temple sits on an islet in the swamp, but the latter has mainly been altered over time. The island is a brick mound, a remnant of the former temple. On top of the mound sits Buddha in the Phra Palelai posture. Old bricks are still visible underneath the construction.
Phra Palelai depicted a posture of the Buddha Shakyamuni in one episode of his life when he sat in the Parileyyaka forest, and an elephant offered him a sugar cane while the monkey offered him a honeycomb.
Wat Jan shows on the 19th century map in the middle of the swamp in a north-south alignment between Wat Sangkha Pat and Wat Saphan Nak. The temple is depicted with a chedi and vihara with the entry to the east.
Phraya Boran Ratchathanin [PBR] depicts the site on his map drafted in 1926 CE precisely in the location we can find today and mentions it had not been excavated.
The Fine Arts Department [FAD], drafted in 1957 CE and found in the ‘Guide to Ayudhya and Bang-Pa-In,’ shows a ‘Wat Chand Torn’ but situates it on the bank of the swamp and thus on the mainland. [1]
All later FAD maps show Wat Jan as an Islet in the swamp. Its historical background and period of construction are unknown.
The site is in geographical coordinates: 14° 21' 22.65" N, 100° 33' 44.18" E.