Vat Phou is a ruined Khmer Hindu temple complex in southern Laos and one of the oldest places of worship in Southeast Asia. It is at the base of mount Phou Khao, some 6 kilometres (3.7 mi) from the Mekong in Champasak province.

Champasak is a province in southwestern Laos, near the borders with Thailand and Cambodia. It is one of the three principalities that succeeded the Lao kingdom of Lan Xang. As of the 2015 census, it had a population of 694,023. The capital is Pakse, but the province takes its name from Champasak, the former capital of the Kingdom of Champasak.