This spectacular temple on a hillside was designated a World Heritage Site in 2002. It is a dramatic complex of temples, steps, statues, and lakes stretching up a mountainside. It is one of the historical highlights of a visit to Laos.

Wat Phou is one of a chain of spectacular Khmer ruins spanning Thailand, Cambodia, and Laos dating back from height of the Angkor empire when the Khmers ruled from the South China Sea to the Andaman sea and as far north as Burma. It has a more run-down feel than either Phimai or Phanom Rung in Thailand and certainly has yet to benefit from the energy of conservation that is taking place in Angkor Wat, although things are moving along. Wat Phou is situated at the base of Mount Phou Kao, 6km (3 3/4 miles) west of the Mekong. There was a temple on this site as early as the 5th century, but the ruins you see now are from the 11th century to the 13th century. The temple is unique in structure, all the parts leading to a shrine where a Shiva lingam (sacred Hindu phallus) was anointed with water from a mountaintop spring. The temple later became a center of Theravada Buddhist worship. It still is. In addition to interested tourists both local and foreign, many come here to make merit.

Initially Wat Phou was linked with the city of Shrestapura, which lay on the bank of the Mekong River due east of Mount Lingaparvata (which is now called Phou Kao). By the end of the 5th century the city was already the capital of a kingdom, which connected with the pre-Angkorian kingdoms of both Chenla and Champa. The first structure on the site was constructed at this time. The mountain was considered a home of Shiva and the river an echo of the holy Ganges.

Shrestapura was then superseded by a new city in the period of Angkorian dominance. The original buildings were replaced, recycling some of their stone blocks. The temple now seen was built primarily during the Koh Ker and Baphuon era of the 11th century. Some alterations were made during the following 2 centuries, before the temple, like most in the empire, was converted to Buddhism under Jayavarman VII. This carried on after the Lao superseded the Khmer. Like most Khmer temples Wat Phou faces east (although it's about 8 degrees off since it is aligned with the river). Including the barays (the lakes that are a feature of Angkorian temples) it stretches 1.4km (3/4 mile) east from the source of the spring, past the base of the cliff and then 100m (320 ft.) up the hill. The accompanying city used to lie east of the temple, on the west bank of the Mekong, while a road south from the temple itself led past temples, its ultimate destination being Angkor itself. Approached from that lost city, the first part of the temple you reach are the barays. There is now one that still contains water. There used to be further reservoirs north and south of this and on each side of the approaching causeway.

Past the main baray, the two palaces flank a central terrace. They are known as the north and south palaces; it is thought they were the men's palace and the women's palace. The term "palace" is loosely used here. Their purpose actually remains unknown. The gender classification is also likely to be apocryphal. Each is made up of a courtyard with a corridor and entrance on the side and false doors at both the east end and the west end. The courtyards of both buildings were built of laterite although the walls of the southern palace were made of sandstone. Both buildings are fenced off and appear to be in a fairly derelict state although the northern palace is in a slightly better condition. The palaces are noted mainly for pediments and lintels.

The next terrace is home to a small shrine to Nandi the bull (Shiva's runaround vehicle in Hindu mythology). The road connecting Wat Phou and Angkor ran south from this temple. As you continue west, more staircases (with tough climbing!) lead up to yet more terraces.

In the penultimate temple a lintel portraying the god Vishnu on Garuda (Vishnu's runaround vehicle, a splendid bird) is found on the northeast wall.

After a hard, sweaty climb (bring both a hat and plenty of water) you reach the main sanctuary culminating in the seven sandstone tiers of the upper terrace and the final sanctuary representing heaven. There are great views of the plain below from here. The sanctuary is made up of two parts. The front section, of sandstone, contains Buddha images, while the rear part of the structure, which used to be home to the Shiva lingam, is empty. Water from the spring emerging from the cliff about 60m (37 ft.) to the southwest of the sanctuary was once channeled along stone aqueducts into this rear chamber, providing continuous bathing to the holy lingam. The sanctuary was built later than the north and south and belongs to the Baphuon period of the later part of the 11th century. The east side features three doorways from south to the north. The pediments show Krishna defeating the naga (snake) Kaliya, the god Indra riding Airavata, and Vishnu astride Garuda. The doorways to both north and south feature ornate inner and outer lintels with scenes from Hindu mythology, some of which are fairly violent in nature.

There is a Buddha footprint on the face of the cliff, and also boulders fashioned to resemble elephants and a crocodile. It is said that the crocodile stone may have been the scene of human sacrifice.

There is an interesting museum on-site, which is well worth a visit. A major festival is held at Wat Phou each March. During the festival, there are not only religious ceremonies but also exhibitions of traditional sports such as elephant racing, horse hockey, boat racing, and others.