Wat Phu is a ruined Khmer Hindu temple complex at the base of Phu Kao mountain in Champasak province, about 45 kilometres south of Pakse. The oldest structures date from the 6th century, predating Angkor Wat by several hundred years. The site climbs a forested hillside in three terraced levels, with carved lintels, galleries, and a sanctuary at the top where a holy spring emerges from the rock.
Look for the crocodile stone and the elephant sculpture near the summit. The views over the Mekong plain from the upper level are beautiful. A small museum near the entrance displays artifacts from the site with English explanations. The annual Wat Phu Festival in February draws pilgrims and features traditional music and buffalo fighting.
The site is easily reached as a day trip from Pakse. You can arrange transport through guesthouses or take a local bus to Champasak town and hire a tuk-tuk the last few kilometres.