Wat Tamnak, or the Monastery of the Royal Residence, was situated off the city island in the southern area of Ayutthaya, west of the Khu Cham (1) and south of the Chao Phraya River in the Samphao Lom Sub-district (2).
The monastery was situated just southwest of Wat Phutthaisawan and northwest of Wat Kratoe.
Except for some traces of shattered bricks, nothing of the monastic structure remains at ground level.
Its historical background and period of construction are unknown.
The temple could have been related to Wat Phutthaisawan. As the translation of the word 'Tamnak' literally means 'Pavilion', the structure was maybe a kind of Royal Residence for the Ayutthayan Kings when visiting Wat Phutthaisawan, or the location where the king stayed when following the construction of Wat Phutthaisawan. Such pavilions were found, for example, near Wat Maheyong, Wat Kudi Dao and Wat Chai Watthanaram.
Wat Tamnak is indicated on Phraya Boran Ratchathain's map drafted in 1926 CE and later on Fine Arts Department maps.
The site was in geographical coordinates: 14° 20' 16.89" N, 100° 33' 24.13" E.