How archaeologists found the lost medieval megacity of Angkor

The ornate, pinecone-shaped towers of Angkor Wat in Cambodia float above a vast temple complex of shrines, pools, houses, and a perfectly square moat. Today, only a small number of monks remain within the temple walls. The remaining structures have been reclaimed by trees whose roots wind around the stone like cellulose tentacles. Archaeologists have long wondered what life was like here when Angkor was the cosmopolitan heart of the Khmer Empire in the 12th and 13th centuries. Why did so many people abandon this place in the 15th century, never to return?