The Persian Empire was one of the most mysterious civilizations in the ancient world. Persia became an empire under the Cyrus the Great, who created a policy of religious and cultural tolerance that became the hallmark of Persian rule. Engineering feats include an innovative system of water management; a cross-continent paved roadway stretching 1500 miles; a canal linking the Nile to the Red Sea; and the creation of one of the Seven Wonders of the World, the Mausoleum of Maussollos. The rivalry between Persia and Athens led to a 30-year war known as the Persian Wars, the outcome of which helped create the world we live in today.