At the southeast edge of town lies the huge bell-shaped chedi of Wat Ya Chai Mongkon. The chedi was built in 1592 by one of Ayutthaya's greatest kings, Nareusan the Great, to commemorate a victory over the Burmese won in the same year. The temple itself was established earlier, in 1357, by King Ramathibodi as a meditation site for monks returning from pilgrimages to Sri Lanka.
The temple is still functioning, and has taken on a role as a museum about King Nareusan as well. A very modern building in the basic shape of a wiharn has been built behind the temple in a formal garden.