At the height of its glory in the 7th and 6th centuries B.C.E., the ancient city of Babylon was the largest and wealthiest in the world. Under the ruthless and ambitious King Nebuchadnezzar II, the sprawling settlement in modern-day Iraq grew into a major city as large as Chicago, and boasted towering temples, ornately tiled palaces and imposing city walls thick enough for two chariots to pass each other side by side.