The royal city of Angkor Thom (near Angkor Wat) was built in the 12th & 13th centuries, centered around the great temple called the "Bayon" (more later). This is the South Gateway to the city, one of five in the city walls. King Jayavarman VII, who's responsible for much of Angkor Thom, really liked giant faces for some reason. (I can understand it - they look really cool; though admittedly he probably had other reasons.)