This temple is more interesting for its story than for its architecture. There are many different versions but all concur that in 1566 when King Setthathirat founded the temple, Si Muang was a young pregnant woman in a nearby village. According to local superstition that held sway at the time, it was necessary to appease the angry spirits with a human sacrifice when the ground was first consecrated and the pillar marking the foundation of the city was built. Si Muang jumped into a hole in the ground before the pillar was lowered and was crushed to death by the rocks thrown on top of her or by the lowering of the pillar itself. To this day, Si Muang is still worshiped as a kind of patron saint, and the wat that is constructed on the place where she supposedly died is named after her, as is the surrounding village or "ban." There is no sign here to recount the story of Si Muang. There is only a pile of old bricks next to a small statue of her at the back of the temple. The reality is that given that Wat Si Muang is built on the site of a previous and far more ancient Khmer temple it is likely that if there is any truth to the legend it occurred far longer ago than the time of King Setthathirat.
The original wat was destroyed in 1828 when the Thais ravaged Viang Chan. This building was constructed under the French in 1915. Both the pillar and a nearby Khmer style chedi probably date from the Khmer era. There is also a Buddha image that may well be from the original structure and survived the destruction wrought by the Thais. It is thought to have mystical powers. All in all Wat Si Muang is considered to be a place of very powerful magic.