Wat Si Muang or Simuong is a Buddhist temple in Vientiane, the capital of Laos, 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.
A statue of King Sisavang Vong stands in front of Wat Simuang. 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.