Prang Ku (stone tower) or Nong Ku Palace at Ban Nong Ku was constructed in the 12th/13th centuries. By its architectural style it is believed to be an arokayasala (medical station/hospital) built during the reign of King Jayavaman VII (1181-1218). Prang Ku is currently located in Wat Si Rattanaram built in 1957. Prang Ku consists of a single tower and associated building to the southeast as well as a pond outside its walls. The monument is Khmer style and currently in relatively good condition. It was built of laterite with sandstone doorways and lintels. The entrance with balcony is on the east side with false gates on the other three sides. The upper roof structure has collapsed and only three levels of the structure remain intact. An image of Indra riding on Erawan elephant, was found inside the tower. There are two pieces of door frame, one of them carved with the figure of a hermit at the bottom. In addition a linga was found inside the tower. The associated building was also built in laterite facing west with a cross-shaped entrance gate in the middle of the wall to the east. There are two small chambers, each in the middle of the north and east walls. It is assumed that this monument was structured with wood as there are four post holes found around the structure. The outstanding feature of Prang Ku is that it represents a hospital plan that was typical under Khmer cultural influence in the 12th/13th centuries. Currently there are 31 of these ancient hospitals discovered in the northeastern region of Thailand. Prang Ku was officially registered as a national ancient monument in March 1935.
This unusually long description of Prang Ku by the 9th Regional Office of the Fine Arts Department based in Ubon Ratchathani suggests that a significant amount of work has been carried out at this site recently.