- Angkor Thom was the last and most enduring capital city of the Khmer empire. It was established in the late twelfth century by king Jayavarman VII. It covers an area of 9 km², within which are located several monuments from earlier eras as well as those established by Jayavarman and his successors. At the centre of the city is Jayavarman's state temple, the Bayon, with the other major sites clustered around the Victory Square immediately to the north.

- The city lies on the right bank of the Siem Reap River, a tributary of Tonle Sap, about a quarter of a mile from the river. The south gate of Angkor Thom is 7.2 km north of Siem Reap, and 1.7 km north of the entrance to Angkor Wat. The walls, 8 m high and flanked by a moat, are each 3 km long, enclosing an area of 9 km². The walls are of laterite buttressed by earth, with a parapet on the top. There are gates at each of the cardinal points, from which roads lead to the Bayon at the centre of the city. As the Bayon itself has no wall or moat of its own, those of the city are interpreted by archaeologists as representing the mountains and oceans surrounding the Bayon's Mount Meru. Another gate — the Victory Gate — is 500 m north of the east gate; the Victory Way runs parallel to the east road to the Victory Square and the Royal Palace north of the Bayon.

- The faces on the 23 m towers at the city gates (which are later additions to the main structure) take after those of the Bayon, and pose the same problems of interpretation. They may represent the king himself, the bodhisattva Avalokiteshvara, guardians of the empire's cardinal points, or some combination of these. A causeway spans the moat in front of each tower: these have a row of devas on the left and asuras on the right, each row holding a naga in the attitude of a tug-of-war. This appears to be a reference to the myth, popular in Angkor, of the Churning of the Sea of Milk. The temple-mountain of the Bayon, or perhaps the gate itself, would then be the pivot around which the churning takes place. The nagas may also represent the transition from the world of men to the world of the gods, or be guardian figures. The gateways themselves are 3.5 by 7 m, and would originally have been closed with wooden doors. The south gate is now by far the most often visited, as it is the main entrance to the city for tourists.

- At each corner of the city is a Prasat Chrung — corner shrine — built of sandstone and dedicated to Avalokiteshvara. These are cruciform with a central tower, and orientated towards the east.

- Within the city was a system of canals, through which water flowed from the northeast to the southwest. The bulk of the land enclosed by the walls would have been occupied by the secular buildings of the city, of which nothing remains. This area is now covered by forest.

- Other than the Bayon, all the main sites are located west or east of the Victory Square. From south to north these are to the west Baphuon, the Terrace of the Elephants, Phimeanakas and the Royal Palace, the Terrace of the Leper King, Tep Pranam and Preah Palilay; to the east, the Prasats Suor Prat, the South Khleang, the North Khleang, and Preah Pithu.

- Recently, it has been noticed that on one of the ruins, there appears to be a dinosaur carved into the wall. This is most intriging considering the site is centuries old and that the dinosaur carving is surrounded by animals of today, such as elephants, snakes, horses and various other creatures.