Of all the superpowers, which one has had the most net positive effect on the world?

Athens were great before Peloponnesus War. It ruled by law instead of tyranny.

.. Rome was great during its growth phase. It had a robust republican system, built roads and aqueducts, emancipated the conquered people, and for the first time in history, provided a path for them to become full Roman citizens. This was the first time when being conquered did not automatically mean death and slavery. It meant that one paid the price, and then had a chance to become a full Roman citizen and even rose up to be the Emperor.

.. The commonality here is obvious – given the existing “norm”, for a nation to become great, it has to offer something better than “the norm”, both to themselves and to others. That was how these nations gained power and influence. But once a nation becomes great, it invariably tries to hold on to what it has by any means necessary, thus it becomes a conservative power for status quo, instead of incremental improvement.

 

Roman Empire Depended Upon Bureaucracy & Navy

The Romans, like all great Empires (save a few exceptions like the Mongol and not even them in totality) actually won because of their bureaucracy- the masses of overweight, underpaid, pasty clerks sitting in warehouses across the Empire counting pennies all day long.

.. Defending ‘land’ is a very modern style of thinking. The Ancients- despite all the poetry they wrote- never defended land. They defended cities, bridges, factories- but never land!

.. If the Mongols had invaded, Rome would’ve simply withdrawn from those lands, allowed the Mongols to bleed themselves out, & shuttled themselves into their port-city-citadels.With navies, there was no way the Mongols could’ve sieged them successfully.