LSE4335199 La congiura dei Pazzi. The conspiracy (conspiracy or conspiracy) of the Pazzi. On Sunday, April 26, 1478, in Florence, a heated-up occurred during Mass in the Cathedral of Florence (Duomo santa Maria dell Fiore). It ended in the death of Julien de Medicis (Giuliano de Medici) (1453-1478). Engraving to illustrate Histoire des popes by Maurice Lachatre (1814-1900), librairie du progres, Paris. by French School, (19th century); Private Collection; (add.info.: La congiura dei Pazzi. The conspiracy (conspiracy or conspiracy) of the Pazzi. On Sunday, April 26, 1478, in Florence, a heated-up occurred during Mass in the Cathedral of Florence (Duomo santa Maria dell Fiore). It ended in the death of Julien de Medicis (Giuliano de Medici) (1453-1478). Engraving to illustrate Histoire des popes by Maurice Lachatre (1814-1900), librairie du progres, Paris.); Photo by Leonard de Selva; French, out of copyright.