When you walk into the Hagia Sophia in Istanbul, you're walking into history. Few structures in the world evoke raw emotion, but the Hagia Sophia's splendor and past manage to do so effortlessly. The Hagia Sophia was once a church. Later it was turned into a mosque, and now it serves as a museum for all to enjoy. It presents history of both the Ottoman and Byzantine empires, both of which once called Istanbul home.