Mona Lisa

Leonardo da Vinci met Francesco del Giocondo when he returned to Florence from Milan in the spring of 1500.

An excerpt from the article 38 facts about Mona Lisa
Without work or money, he stayed at the convent at Santissima Annunziata, where he promised to paint an altar painting in exchange for hospitality. Leonardo's father introduced his son to Lisa's husband, who supplied the convent with fabrics. Perhaps it was then that he proposed to paint a portrait of Gioconda.