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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?