Want to see the longest wall ever made in the world? Well, the Great Wall of China is the longest structure that ever existed. The wall was built more than 2300 years ago and leaders from around the world all agree that it should be considered a world treasure. It was built over the course of hundreds of years by the rulers of China. Can you guess why this monstrous wall was built across China? TheGreat Wall of China was built toprotect the Chinese Empire from invasion by its enemies in the North.Read to find...