Angkor Thom is a walled city (the last capital of the Khmer empire) and each side is about 2 miles long, so it's huge and will take a goodly amount of time to properly explore. Bayon sits in the exact center and begin your visit there at dawn when the early morning light shines on the stones. The city is laid out as a model of the universe and construction began around 1,000 years ago. The area to the north of Bayon is best seen by taking your time and walking around. Unfortunately some areas that were previously open to passage are now blocked off but there is still plenty to see. Be sure to climb to the top of the temples which allow access. A myriad of temples awaits your discovery! I never tire of them.