Angkor Wat was first a Hindu, then subsequently a Buddhist, temple complex in Cambodia and the largest religious monument in the world. The temple 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. Breaking from the Shaiva tradition of previous kings, Angkor Wat was instead dedicated to Vishnu. As the best-preserved temple at the site, it is the only one to have remained a significant religious center 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. [source]

The outer wall, 1024 m by 802 m (1120 x 877 yards) and 4.5 m high, is surrounded by a 30 m apron of open ground and a moat 190 m (207 yards) wide. The outer wall encloses a space of 820,000 square metres (203 acres).