Angkor Thom is undeniably an expression of the highest genius. It is, in three dimensions and on a scale worthy of an entire nation, the materialization of Buddhist cosmology, representing ideas that only great painters would dare to portray.
Angkor Thom, the last capital of the Khmer Empire, was a fortified cit enclosing residences of priest, officials of the palace and military, as well as buildings for administering the kingdom. These structures were built of wood and have perished but the remaining stone monuments testify that Angkor Thom was indeed a "Great City" as its name implies. Temples inside the walls of the city described are Bayon, Phimeanakas, Baphuon, Terrace of the Elephants, Terrace of the Leper King, Prah Palilay, Tep Pranam and Prasat Suor Prat.
Symbolically, Angkor Thom is a microcosm of the universe, divided into four parts by the main axes. The temple of the Bayon is situated at the exact center of the axes and stands as the symbolical link between heaven and earth. The wall enclosing the city of Angkor Thom represents the stonewall around the universe and the mountain ranges around Meru. The surrounding moat (now dry) symbolizes the cosmic ocean.
https://www.tourismcambodia.com/attractions/angkor/angkor-thom.htm