At the time, the whole world had a total population of about 5 million people. So both this city and modern-day NYC would have about 0.1% of the global population. The comparison seems apt.
- A constant agrictultural surplus being able to support a city of this size.
- A political system with some form of taxation and probably a kind of military and/or police.
- A construction and manufacturing industry.
This is all really basic stuff for a modern society, but we only got here, because we built on giants.