The largest site in the Angkor Archaeological Park, the name Angkor Thom means Big Angkor. It is a huge walled city with a moat, and was the last great capital of the Angkorian Empire. When Jayavarman VII defeated the Cham invaders in 1181, and recaptured the Angkorian capital, he instituted a massive building program throughout the empire. He constructed Angkor Thom as the new capital city, and encompassed the already existing temples of Baphuon and Phimeanakas. At its zenith, it is estimated that the city had a population of almost one million.