Angkor Thom is Khmer for "Greater City" — part of the Khmer Empire extending from Angkor Wat, about 2 km away, and home to the Bayon Temple.
The city is enclosed by squared walls and a moat. All inroads were guarded by massive gates: South, East (the Gate of the Dead), Victory, North, and West. The causeways leading to each gate are lined with two rows of stone giants holding a churning sea of milk — 54 devas (gods) and 54 asuras (demons) on opposing sides.
The South Gate is the closest Angkor Thom entrance from Angkor Wat and therefore the most visited. It is the only gate with a paved access road bridge, and the only one restored with all 104 heads of devas and asuras intact — restored in the 1950s. It's a tourist destination in its own right, though that makes it difficult to photograph without crowds.
The other gates — Victory, North, East, and West — receive far less traffic, and each has its own quiet character worth seeking out.