Angkor Wat was built about 900 years ago, starting around 1113. It was designed for a Khmer king and built by tens of thousands of workers. They carved the stone by hand - every wall, every tower and every doorway has detailed patterns of gods, dancers and animals cut right into the rock.
The temple has five towers shaped like lotus flowers. The tallest one is about 65 metres high - as tall as a 20-storey building. When the sun rises over the main pool in front of the temple, the towers reflect perfectly in the still water, which is why dawn is the most popular time to visit.
Angkor Wat is part of a much larger area called the Angkor Archaeological Park, which is as big as a large city. Inside the park there are dozens more temples hidden among the trees. Some of them still have roots and branches of giant trees growing right over the walls.
Today, Angkor Wat appears on the Cambodian flag - the only building in the world to appear on a national flag. It is a symbol that Cambodians are very proud of, and every year more than a million visitors come from around the world to see it.