Angkor Wat is in Cambodia, 5.5 km (3.5 mi) north of Siem Reap. It's the centerpiece of the Angkor Archaeological Park (400 km²), a UNESCO World Heritage Site.
Built early 12th century by King Suryavarman II as a Hindu temple (Vishnu), later Buddhist. Largest religious monument on Earth (162.6 ha / 402 acres). Symbol of Cambodia (on flag).