Next to Wat Phra Si Sanphet, this sanctuary hall houses one of Thailand's largest bronze Buddha images, dating to the 15th century, most likely. Coated in gold, the 12.5m-high figure (17m with the base) was badly damaged by a lightning-induced fire around 1700, and again when the Burmese sacked the city. The Buddha and the building were repaired at various points in the 20th century and it's now one of Ayuthaya's must-sees.
In 1956, the Burmese Prime Minister donated 200,000B to restore the building, an act of belated atonement for his country's sacking of the city two centuries before.