Wat Okat or Wat Okat Si Bua Ban is the old sacred temple of Nakhon Phanom Province. The temple houses two revered Buddha images, "Phra Tio" and "Phra Thiam", which are situated together, as well as beautiful murals. Interesting sights inside the temple include the two identical "Phra Tio" and "Phra Thiam" Buddha images in Mara Vichaya Posture. Housed in the Busabok pavilion in front of the principle Buddha image inside the temple's main hall, the two ironwood statues are 39 centimeters high and 60 centimeters tall. Phra Thiam is located on the right side of the principle image, while Phra Tio is on the left. According to a legend, the images were built in the time of Si Khotrabun Kingdom when King Si Khotrabun demanded to have a royal barge constructed. Once the vessel was completed, they pushed it onto Khong River by putting numbers of round logs underneath the barge as laborsaving tools in moving. One log of Tio wood didn't move as they pushed and kept straying away from the direction. It took a long time to finish moving the barge onto the river. They believed that there was a guardian spirit in that Tio wood. The King, therefore, decided to have the Tio wood carved into a Buddha image in the year 784 and organized a ceremony to celebrate the Buddha statue of the kingdom. In the reign of the next king, King Khattiyawong, a fire incident burned down the hall of Phra Tio. The King ordered to have an imitation of Phra Tio carved from a sacred wood. However, Phra Tio statue was later found in Khong River. It was brought to house alongside with the new Buddha image which was named as "Phra Thiam."Beautiful murals inside the main hall of the temple depict the life of Lord Buddha. Wooden plates on top of each pole are painted with pictures of angels inside glass pavilions, while the wall is painted with golden stars on red background. Each pole is painted in colorful Thai patterns. Both Buddha images are sacred icons of the city.