Built during early Rattanakosin Era, Wat Thammakhosok is located on Si Uthai Road in town. It used to be the site for the Oath of Allegiance Rituals for provincial officials as well as the execution site for convicts in the past. In the Ubosot are the finest wall murals of the town which were made by the late Ayutthaya period artists. They portray Buddhist history and likeness of celestial spirits alternating with religious paraphernalia which are the handiworks of later painters.
Within the Wihan are housed about twenty ancient Buddha statues. Over the windows outside the building are plaster relieves depicting the epic Ramayana. The door panels are wood carved in floral designs. The small Kuti (monk’s quarters) next to the bot represents the delicate craftsmanship of the early Rattanakosin Period.