In 1468 it was decided that the appropriate decoration for the lantern Fillippo Brunelleschi had created around 30 years prior was to be a bronze ball (palla) and cross.  A competition was created to determine which artist would be given the honor of creating the palla that was to adorn the top of the Florence Duomo.  While Andrea del Verrocchio was not the winner of the competition, he received the commission to make the palla after the first attempt by another artist was unsatisfactory.  September 10, 1468 marked the day that Verrocchio began his project, along with his colleagues which included a teenage Leonardo da Vinci.

Works Cited:

Bambach, Carmen. Leonardo Da Vinci Master Draftsman: Catalogue to an Exhibition at The Metropolitan Museum of Art, New York 2003. Yale University Press, 2003.

Neilson, Christina. Practice and Theory in the Italian Renaissance Workshop: Verrocchio and the Epistemology of Making Art. Cambridge University Press, 2019.