Bayon Temple - ប្រាសាទបាយ័ន was the first temple I visited on my first trip to Cambodia in 2013, when it was undergoing major restoration work which meant that many sections were inaccessible and heavy equipment obscured parts of the view. It’s one of several temples within Angkor Thom - អង្គរធំ, and is 1.7 KM in a straight line north from the West Gate of Angkor Wat. Angkor Thom dates from the late twelfth century and the last temple (Mangalartha) constructed within the city was dedicated in 1295. It’s estimated that Bayon was constructed sometime during the late twelfth and early thirteenth centuries and was the “last state temple built at Angkor, and the only Angkorian state temple to be built primarily as a Mahayana Buddhist shrine dedicated to the Buddha”.
See Wikipedia and Asian Historical Architecture.