Set in the center of the historical park, right across from Wat Phra Si Sanphet, with its classic Ayutthaya style stupas, is the towering prang of Wat Phra Ram. Built in 1369 on the site of the first Ayutthaya king's cremation, the temple was restored in the 15th century and extended throughout the Ayutthaya period.
Although you now enter the temple complex on the western side, the original temple faced east, as you can tell from the ruins of the portico on the eastern side. The shells and foundations of many chapels and other buildings can be seen around the grounds. Only a little of the original stucco work remains, but there's enough to get an idea of how rich the detail must have been.
Next to the temple is a rather large park with a sizable lake, called Beung Phra Ram. The park may have been part of the temple in ancient times.
There is a fee of 50 Baht (1.28 USD) to enter the grounds of Wat Phra Ram. The temple is open from 8:30 am to 5:00 pm.