The cardinal was a trusted advisor and a protégée of the de’ Medici family, first of the cardinal and later of the Duke of Tuscany Ferdinand de’ Medici (Ferdinando de’Medici).  An intellectual and a protector of Galileo, an enthusiast of art and music, from our point of view, he is important mainly as a patron of Caravaggio. Chroniclers also speak of his frugal and modest lifestyle and a great passion for the fashionable at the time madrigals, which spoke of feelings, including the most important one – love. The cardinal himself played Spanish guitar and possessed a collection of musical instruments. Apart from music, but also alchemy, his main passion was ancient art, as well as painting. At the end of his life, his collection featured approximately six hundered paintings. Besides Caravaggio he also possessed paintings of Titian, Giorgione, as well as Dutch painters.

In 1596 del Monte purchased the park arrangements along with a villa at the Porta Pinciana gate, where in a small park palace (Casino Ludovisi), he created an alchemical study and a small salon, whose rather bold decorations were entrusted at the end of the XVI century to Caravaggio.