almost contemprory. the main tempe was later than big temple
The principal temple, Angkor Wat, was built between 1112 and 1150 by Suryavarman II. With walls nearly half mile on each side, something like 15o acres.
Angkor Wat portrays the Hindu cosmology with the central towers representing Mount Meru, home of the gods; the outer walls, the mountains enclosing the world; and the moat, the oceans beyond.