The site's history dates back to the 9th century, when a place of worship dedicated to the Hindu god Shiva was constructed. Khmer King Suryavarman I (1002-1050) extended the temple, located on top of a spectacular cliff some 625 metres above sea level.

Thanks to its remote location, the temple's architecture is very well preserved. The main temple complex runs for 800 metres along a north-south axis up the hill.

France, the colonial power ruling Cambodia, and the then-kingdom of Siam agreed in the early 20th century to demarcate the border. The guiding principle that the watershed of a mountain range should be followed by the border line would put most of the now- disputed areas around the temple in Thai territory.

However, a French map from 1907, which was used for the later International Court of Justice ruling, differs.

At Cambodia's independence in 1954, Thai troops occupied the temple area. In Thai, the temple is called Phra Viharn.

In 1962, the International Court of Justice awarded Preah Vihear to Cambodia. Thailand had not challenged Cambodia's sovereignty over the temple for decades, the court said in its ruling. However, it did not rule on a nearby plot of land, also claimed by both countries.

Cambodia's Khmer Rouge used the temple as a stronghold until the 1990s. It is also believed to have been the last place to fall to the regime in 1975.

Thailand claims a 4.6-square-km plot of land adjacent to the temple and has blocked Cambodian's efforts to turn the site into a tourism attraction until the border dispute is settled.

The border is yet to be demarcated. The main access to the temple is on Thailand's side of the border, while at the Cambodian side the sheer cliff makes access difficult.

UNESCO in July 2008 declared the edifice a World Heritage Site despite Thai objections. Clashes have flared up in the disputed area several times since.