Tham Piu Cave is a natural limestone cave located approximately 20 kilometers from Phonsavan, the provincial capital of Xieng Khouang. The cave has been transformed into a memorial site for the victims of the Secret War in Laos. During the Vietnam War, the cave was used as a refuge, makeshift hospital, and school by US Forces. In 1968, it was devastated by a missile fired into the small opening, killing more than 300 people. Today, Tham Piu Cave has a small interpretive center where you can view some artifacts as well as some horrific pictures of the devastation that was incurred on 374 innocent victims of the missile attack.