Wat Si Muang or Simuong is a Buddhist temple in Vientiane, the capital of Laos. This temple was built in 1563. Located near the eastern entrance to the city centre, on the road leading from the Friendship Bridge to Thailand, the small temple was built on the ruins of a Khmer Hindu shrine, the remains of which can be seen behind the ordination hall.
Inside, the sim is unusually divided into two rooms. The front room of the sim is quiet with usually a monk on hand to give blessings and the rear room houses the large main altar, which is crowded with Buddha images. There is the legend that pregnant women at the time of construction were given to as sacrifice to God.