Find here under the temple sites of the Historic City of Ayutthaya, a UNESCO World Heritage Centre (WHC 576) since 13 December 1991 CE. The Thai authorities submitted the boundaries of the World Heritage Historical Park to UNESCO on 11 October 1991 CE. [1]
After studying various old and new maps, I concluded that the Historical Park has 82 temple sites, of which 45 are ruins restored by the Fine Arts Department – 3rd Region and 37 other locations where temples once stood but disappeared over time.
Within these WHC boundaries, numerous temple ruins - mapped in the 19th and early 20th century centuries - vanished mainly due to the urbanisation of the area.
The Ayutthaya monasteries were sacked and plundered by the Burmese and further dismantled after the fall of Ayutthaya to reconstruct the Siamese capital in Bangkok. Most parts of the wall and the forts were dismantled in the reign of King Rama I (1782 - 1809 CE), who had the bricks taken to be used in constructing the city walls for the new capital in Bangkok. In 1784 CE, bricks from the ruins of Ayutthaya were used to build a barrage in the Lat Pho Canal at Phra Pradaeng to halt the intrusion of saline water farther inland.
Another round of collecting building material occurred in the reign of King Rama III (1824-1851 CE) when remaining bricks and laterite stones, including those of the Thamnop Ro causeway and the Elephant Bridge, were sent down to Bangkok to be used in the construction of a giant stupa, a copy of Ayutthaya's Chedi Phukhao Thong, called Wat Saket which collapsed into rubble. Ayutthaya's temple bricks were also used to strengthen the bed of the Bangkok - Ayutthaya - Lopburi railway track at the end of the 19th century. When, in the last century, the demand for antiques increased, and the amulet markets mushroomed, Ayutthaya's ruins were plundered one more time.
During the fifties and early sixties, witnesses recount, it was common for locals in the Ayutthaya area to collect the bricks of the ruins. The Department of Religious Affairs agreed to allow merchants to dig up bricks from abandoned temples and load them onto boats to sell. The bricks were locally used to help expand other temple sites but were mostly sold to contractors and shipped on a large scale as there was a demand from Bangkok.
[1] References: Note 826/1530 Fine Arts Department - transmitted 17 August 1987. Historic City of Ayutthaya 2533 / page 19.]