The Angkor Wat
The Angkor Wat is of course the first in the list when visiting Cambodia. It is a UNESCO World Heritage Site and one of the world’s largest religious monument. Seriously, you may have to visit it for 3-4 days to tour the whole place. Originally a Hindu temple, after the disintegration of the Khmer empire, it has been repurposed as a Buddhist Temple. Be prepared to walk for a few kilometres and climb steep staircases.