Bayon is a well-known and richly decorated Khmer temple built in the late 12th or early 13th century as the official state temple of the Mahayana Buddhist King Jayavarman VII. The Bayon stands at the centre of Jayavarman's capital, Angkor Thom. Following Jayavarman's death, it was modified and augmented by later Hindu and Theravada Buddhist kings in accordance with their own religious preferences.

Bayon was the last state temple to be built at Angkor, and the only Angkorian state temple to be built primarily as a Mahayana Buddhist shrine dedicated to the Buddha, though a great number of minor and local deities were also encompassed as representatives of the various districts and cities of the realm.

It was the centrepiece of Jayavarman VII's massive program of monumental construction and public works, which was also responsible for the walls and naga-bridges of Angkor Thom and the temples of Preah Khan, Ta Prohm and Banteay Kdei.

The Bayon's most distinctive feature is the multitude of serene and massive stone faces on the many towers which jut out from the upper terrace and cluster around its central peak. The similarity of the 216 gigantic faces on the temple's towers to other statues of the king has led many scholars to the conclusion that the faces are representations of Jayavarman VII himself. Others have said that the faces belong to the bodhisattva of compassion called Avalokitesvara.

The most likely explanation is that the faces are of Avalokitesvara modelled with the face of the King, just as his Mother was the model for Prajnaparamita in Ta Prohm, and his Father for Lokesvara in Preah Khan, and they are looking down on his subjects with benign compassion.

The temple is known also for two impressive sets of bas-reliefs, which present an unusual combination of mythological, historical, and mundane scenes. The galleries feature a series of bas-reliefs depicting historical events and scenes from the everyday life of the Angkorian Khmer. Though highly detailed and informative in themselves, the bas-reliefs are not accompanied by any sort of epigraphic text, and for that reason considerable uncertainty remains as to which historical events are portrayed and how, if at all, the different reliefs are related.