Vat Phou (or Wat Phu; Lao: ວັດພູ [wāt pʰúː] temple-mountain) is a ruined Khmer Hindu temple complex in southern Laos. It is located at the base of mount Phu kao, some 6 kilometres (3.7 mi) from the Mekong in Champasak Province. There was a temple on the site as early as the 5th century, but the surviving structures date from the 11th to 13th centuries. The temple has a unique structure, in which the elements lead to a shrine where a lingam dedicated to Lord Shiva was bathed in water from a mountain spring. The site later became a centre of Theravada Buddhist worship, which it remains today.
After the first scientific description on the late 19th and early 20th century there has been little scientific activity at the site until the early 90s. With the Lao-UNESCO projects starting in 1987 and the designation as UNESCO World Heritage Site in 2001 archeological and conservational activities increased heavily.