Why was Babylon considered the richest city?

Babylon is one of the most famous cities of the ancient east, there are even legends about it (the construction of the Tower of Babel). This ancient city was founded in the middle of the 3rd millennium BC. It flourished during the reign of Nebuchadnezzar II (605-562 BC). Then Babylon was the center of a large state, in addition, at that time it was also a cultural and commercial center of the ancient east. This fact undoubtedly affected the well-being of the city. Even when Alexander the Great himself entered this city, he was so impressed by its beauty and wealth that he decided to make it his capital.