Geography
Why Mega Cities Emerge at River Confluences
Quick fact
The confluence of the Rhine and Main rivers is so significant that the city at that point, Frankfurt, became a major financial hub—showing how a watery crossroads can become a center of power centuries later.
Why this is interesting
Think of the world's greatest cities: London, Paris, Cairo, Shanghai. What do they have in common? They all sit where two rivers meet—but why exactly there?