Angkor Wat temple: Built in 12th century during the reign of King Suryavarman II (1112-1150), dedicated to the Hindu God Vishnu. Angkor Wat temple is the main feature of Cambodia tourism, the all-time visited temple among hundreds of Khmer temple ruins.

Angkor, the capital of Khmer empire from 9th to 13th century, ruled a vast territory that is now Cambodia, Vietnam, Thailand, and Laos. During these periods, the Khmers build hundreds of temples and Buddhist monasteries throughout Thailand, Laos, and Cambodia. Despite of Angkor temples are seen sprawling over the hundreds of historical sites in Thailand, Laos, and Cambodia, the main temples featuring Angkor civilization and political culture involving administration and power are located in Siem Reap province. These temple ruins converge in an area of 400 square kilometers just north of Siem Reap town and Tonley Sap lake.

Angkor began in 819 A.D. when King Jayavarman II (802-850) moved a Khmer settlement to Siem Reap province and the settlement became an administrative centre of Khmer empire. During the reign of King Suryavarman II (1113-1150), in which Angkor Wat temple was built, the Chams from Champa from the East (now Vietnam) began armed incursions and sacked Angkor. Following the death of King Suryavarman II and the Cham invasion, Angkor is invaded and ransacked by the Thais, based in western part of the Khmer Empire. These Thai army forces had been employed by the Khmer King to repel the Cham invaders. Thereafter, again and again, the Chams and the Thais invaded and ransacked Angkor.

King Jayavarman VII (1181-1215) who built Angkor Thom fought and repelled the invading Chams and the Thais. The glory of Khmers and Angkor was again restored but the it was short lived. The Empire began to crumble after the death of King Jayavarman VII. The Thais from the west and the invaders from the East, this time the Vietnamese, frequently carried out armed incursions and invaded Angkor and the Khmer Empire's peripheral territory was gradually lost. After the capture of Angkor by the Thais in 1431, Khmers moved their capital from Angkor to Phnom Penh leaving Angkor unoccupied to the mercy of the jungles. From the early 15th century until the late 19th century, the Buddhist monks lived in Angkor and made Angkor the largest religious pilgrimage site in South East Asia