Wat Si Sawai is situated 350 metres south of Wat Mahathat. Its three prangs
(imitating Hindu Shikhara Vimanas) are regarded as ancient monuments of considerable
significance. Demarcated by a wall, the three prangs were built in Lop Buri style.
Their slender forms on low bases are decorated with stucco, with some designs similar to those on Chinese wares of the Yuan dynasty.
A carved lintel depicting the god Vishnu reclining on the Naga seat, fragments of Hindu images, and
linga all indicate that this temple was originally a Hindu sanctuary. It was later transformed into a Buddhist temple with
some expansion of the front part in the form of a vihara.
Situated among magnificent scenery southwest of Wat Mahathat is Wat Si Sawai. Three prangs are surrounded by a laterite wall.
Inside the wall, the viharn in the west, built of laterite, is separate from the main prang which was constructed in Lop Buri or Hindu-style but the others, also constructed beside the prangs, are Buddhist viharns.
The Crown Prince (King Rama VI), found a trace of Hindu sculpture Sayomphu, the greatest Hindu God in this sanctuary. In his opinion this ruin was once a Hindu shrine, but was later converted into a Buddhist monastery.