Constantinople as it would look by air. Wikipedia
The 16 Greatest Cities In Human History -- Business Insider
What New York City was in twentieth century, London was in the the 1900s, Constantinople was in the 600s, and so forth, back to Jericho in 7000 BC.
They were the largest cities in the world, and arguably the epicenters of human civilization. These cities led mankind to new heights of culture and commerce—though in the end each of them was surpassed and some of them destroyed.
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My Comment: I would also add the cities of Athens, Alexandria, and Troy.