Babylon, the ancient city of Mesopotamia, famous for its Hanging Gardens, one of the Seven Wonders of the World, located where what today is Iraq, had a population of maybe 100,000. But this was way back in 3000 B.C. Today, Iraq has a population of 26 million, and has lost its charm.
Athens was all of 50,000 in its heyday 2,500 years ago. It grew to 300,000 by 432 B.C. (only half citizens, as 50,000 were aliens, with 100,000 slaves). Today, while it has lost its dominance, the population is approaching 4 million.
Early in the 17th Century, London became the first city to reach 1 million. Today, nineteen cities have populations ranging from 10 to 25 million.
Conversely, Europe in the 16th Century had 500 autonomous governments. By 1975, this had been reduced to 35, and with the European Union, 27 countries will be reduced to one. But, then, the Soviet Union did increase from one to 15, and there are projections that China could someday suffer the same fate. Irrespective, those Soviet entities will someday all join the EU and those potential Chinese states will link with the budding OU, or, Orient Union. The trend is towards one unifying world government.