Many would argue that he did this only to create what is called a "buffer state" between his own empire and the hostility of Egypt. Under his leadership, Persia gave way to some of the most ingenious engineering the world has ever known. Engineering feats included an innovative water management system; a water channel connecting the Nile to the Red Sea; and the creation of the Mausoleum of Maussollos, one of the seven wonders of the world. Cyrus laid the foundation for a messaging or mail system. In 530 BC, Cyrus the Great died in battle. He did not live long enough to see all that his empire could have become, which is why he was compared to Julius Caesar. At the time of his death, the Persian Empire had three capitals: Babylon, Persepolis and Ecbatana. This left Persia without a leader and started a great war. The future of Persia now hung in the balance as many rivals vied for power. Then Cyrus' distant cousin, who was also a general, rose to consummate power. He became known as Darius the Great. Darius, I began to rebuild the ancient capital of