Angkor Wat is a temple complex in Cambodia and the largest religious monument in the world, on a site measuring 162.6 hectares (1,626,000 m2; 402 acres).

Originally constructed as a Hindu temple dedicated to the god Vishnu for the Khmer Empire, it was gradually transformed into a Buddhist temple towards the end of the 12th century as such it is also described as a "Hindu-Buddhist" temple. 

It was built by the Khmer King Suryavarman II in the early 12th century in Yaśodharapura , the capital of the Khmer Empire, as his state temple and eventual mausoleum. 

As the best-preserved temple at the site, it is the only one to have remained a significant religious centre since its foundation. The temple is at the top of the high classical style of Khmer architecture. It has become a symbol of Cambodia, appearing on its national flag, and it is the country's prime attraction for visitors.

According to en.wikipedia