Wat Chaiwatthanaram in Ayutthaya was ordered to be built by King Prasat Thong in 1630 on the bank of the Chao Phraya River, the reason he built this was to make merit for his mother, entry fee for foriengers is 30baht, although it would be quite easy to sneak in and not bother paying.
In 1767 the Burmese invaded and this Royal Monastry was used as an army camp, unfortuneately Thailand lost this battle and the Burmese looted and damaged many of the artifacts, in the late 1980s early 90s the fine arts dept renovated to the stage it is at now.
Some more links with info and Pictures of Ayutthaya.
A weekend in Ayutthaya with Marmite and Gow
Nice cheap Hotel with air etc in Ayutthaya
Awful Restaurant in Ayutthaya
A Nice Restaurant on the River Banks of Ayutthaya (Kankitti Restaurant, Ayuttaya)
From TAT
Located on the bank of the Maenam Chao Phraya, to the west of the city island is Wat Chaiwatthanaram. Built in 1630 by King Prasat Thong to honor his mother, Wat Chai Wattanaram was conceived as a replica of the Angkor temple. A Royal monastery, the temples unique feature is a huge prang which is surrounded by smaller prangs. This symbolizes Mount Meru, the abode of the heavenly gods. Now restored, the temple is also accessible by a long-tailed boat trip from Chankasem Palace Pier. This 1-hour trip to the temple costs approximately 300-400 bahts (round-trip).
Admission is 50 baht. A package ticket vilid for 30 days is also available at 220 baht each, covering admission to Wat phra Si Sanphet and the Ancient Palace Complex, Wat Mahathat, Wat Ratchaburana, Wat Phra Ram and Wat Maheyong .
Ayutthaya Historical Park provides the audio tour in English described for Wat Phra Si Sanphet, Wat Chai Watthanaram, and Wat Mahathat. Available at Ayutthaya Historical Park ticketing counter. The fee is 150 baht.