He bought in 1565 together with his brother Cardinal Ottavio Cesi, bishop of Todi, the Palazzo Armellini in Borgo, and took charge of the restructuring, relying for the new project to Martino Longhi the Elder, who between 1570 and 1588 oversaw the renovation in its present form.[3] Being like his brother an art lover, he hosted in his palace a large antiques collection and a large library.[3]