Situated among magnificent scenery southwest of Wat Mahathat is Wat Si-Sawai. Three prangs are surrounded by a laterite wall.

Inside the wall, the viham in the west, built of laterite, is separate from the main prang which was constructed in the Lop Buri or Hindu-style, but the other also constructed beside the prangs are Buddhist vihams. The Crown Prince of that time who later become King Rama VI found a trace of the 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