Phra Tamnak Khamyat is located in Tambon Khamyat, 2.5 kilometers west of Wat Pho Thong on Ayutthaya Pho Thong Road. At present only four walls of the royal residence remain. The 10×20 meters royal residence, made of brick and plaster, stands eminent in a paddy field. The artistic beauty still remains e.g. motifs around the window, front and back balcony, was painted in red soil and covered with wooden floor. Regarding his diary about the trip on the Makhamthao River, King Rama V visited Phra Tamnak Khamyat in 1908, he understood that Krommakhun Phornphinit (Prince Uthumphorn or Khunluang Hawat) entered his monkshood at Wat Pho Thong and built this residence for his lodging during the Buddhist Lent since it was a strategic site.
Having seen that the residence was exquisitely constructed, King Rama V then changed his mind. He realized that Krommakhun Phornphinit should not have had this residence built so exquisitely for a temporary lodging or a stronghold. King Rama V surmised that this residence might have been constructed in the reign of King Borommakot as his residence during his frequent visits to this area, in parallel to King Prasatthong who constructed his residence in Bang Pa-In. Due to his preference in this area and paying homage to the reclining in Wat Khun Inthapramun twice, Krommakhun Phornphinit (Prince Utumphorn or Khunluang Hawat) made his loyal subjects and monks to leave Ayutthaya and stayed at Wat Pho Thong Khamyat and Phra Tamnak Khamyat in order to join with Bang Rachan villagers. At present, Department of Fine Arts has renovated and registered Phra Tamnak Khamyat as a historical site.