Pazzi-Verschwörung
In 1478 he was one of the plotters behind the Pazzi conspiracy, a plan to assassinate the two most prominent members of the Medici family in Florence. In addition to conspiring, he was an intended beneficiary, once Lorenzo and Giuliano de' Medici had been killed. Riario would have become Lord of Florence. But the plot failed, as only Giuliano was killed.