Cosimo de' Medici

Born in 1389 to a banking family, Cosimo di Giovanni de' Medici understood that gold could do what armies couldn't. His wealth made him indispensable to Florence's politicians, and through strategic marriages he wove his family into the city's power structure. In 1433 rival factions exiled him, but within a year he was back, and from then until his death in 1464 he ran Florence as its de facto first ruler — never an autocrat, always "first among equals," his proposals still blocked by councils who resented him even as they needed him. He poured over 600,000 gold florins into art and architectu…