For today's Geo Quiz, we're heading to the furthest reaches of the world's biggest forestï¿½ in search of a lost city. The Amazon rainforest covers almost a billion and a half acres of South America. The forest is dense and inhospitable to humans and anthropologists long thought only small, simple societies lived there. But rumors have persisted for centuries of long-lost great civilizations, deep in the Amazon. The World's Marina Giovannelli reports.