The greatest city that had ever been built impressed the widely traveled historian Herodotus so much that he wrote, «It was decorated in such a way that I had never seen in any city.» When he wrote this in the 5th century BC, Babylon was already about 2,000 years old. The first reference to a city with this name dates from about 2500 BC. Babylon peaked under King Hammurabi shortly after 1800 BC and after many years it declined. Nebuchadnezzar II, who ruled from 606 to 562 BC, restored the city to greatness. It fell to the Persians in 539 BC. Greek sailors are said to have been plying the waters of the Euphrates in the 8th century BC. The rise of cities in Greece and Asia Minor in the 6th century BC and the expansion of the Greeks’ trade, beyond the influence of Babylon, contributed to the great city’s decline. When Alexander conquered the city in 330 BC, seven years before his death there, it was a Persian city. All along, the Greeks studied and were influenced by the mathematics, astronomy and astrology, the city planning and the medical knowledge of the Babylonians and other peoples of Mesopotamia. The wise men of Mesopotamia thought up, among other things, the division of the circle by 360 degrees and the division of the year by 12 months. They set out the foundations of astronomy and astrology. They studied diseases and concocted complicated medicines, some of which contained up to 90 ingredients.