Don Tuan Khmer Ruins. Built during the 10th -11th Century, the Khmer Ruins near Ban Phume Sarol () are located at , 350 meters onto the Cambodia side of the distinct watershed border ridge, at an elevation of 250 meters above sea level, 30 meters below and 350 meters southwest of the border ridge. The only road access, however, is from Thailand. Legend tells that in the past a lady known as "Nang Nom Yai" or "Nieng Non dor" (in Khmer), stopped to rest here on her way to visit a king.