There are more than 1,000 temples in Angkor which have been reclaimed from the jungle and some are magnificent architectural gems to rival the best around the world. Recent Satellite photos have revealed that Angkor spread over 400 square miles making it the largest preindustrial center in the world. Here are some of the best. The immense Khmer empire from the 9th to the 15th C century stretched over present day Cambodia, Thailand, Laos, Vietnam all the way to India. At Angkor it created a sophisticated network of hydraulic canals and rice paddies that supported over a million people and left architectural monuments that are as overwhelming as ancient Egypt. The ruins of Angkor have been declared a Unesco World Heritage site. In 1431 enemy armies invaded and sacked Angkor. The population left , the region was abandoned and most of this incredible culture was swallowed up by the jungle.