Wat Phra Sri Rattana Mahathat, or simply 'Wat Yai' to locals, was established in the mid-fifteenth century by the king of Sukhothai. At the center of the temple is a large Khmer style tower (called a prang). Chapels abut the tower on three sides, and the entire grounds are enclosed by a gallery lined with Buddha images.
The chapel on the north side of the tower houses the Phra Chinnarat Buddha image, one of the most famous images in Thailand, and widely reproduced. The local Buddha foundry specializes in reproductions of this image. The chapel also houses display cases showcasing bits of local history. More of the collection is also arrayed around other parts of the courtyard.
Outside the gallery on the east side are the ruins of a large chapel. The standing Buddha image of the chapel has been restored and now stands among the ruins. On the south side of the ruins is the new ordination hall, with a large elegant Buddha image and some interesting murals about life and warfare in old Phitsanulok.
Around the temple is a large market, which gets especially busy during the two annual fairs held in or near the temple. The Phra Buddha Chinnarat Fair is held in January every year in the temple, while the annual boat races use the river immediately in front of the temple in October.