Pietro da Cortona is one of the most important artists of the 17th century in Italy, whose projects were commissioned by leading representatives of the society of major artistic centers, such as Rome and Florence. Ferdinand II. de Medici, who commissioned projects for the Pitti Palace in Florence, is just one of many in the series. In the 17th and 18th centuries, the client was a very important factor in making the final decisions related to a work of painting, architecture or sculpture. In this final paper, an example of an order will be presented for the purpose of a more detailed analysis and explanation of the commissioning practice of the 17th century, and the relationship between the artist and the client. Pietro da Cortona proposed a new facade design for the Pitti Palace, as well as a connection with the outside space, i.e. the garden area. Although the new facade of the Pitti Palace was not built according to his design, Cortona's drawings were preserved and are now kept in the Uffizi Gallery. On the other hand, the fresco cycles performed by Pietro da Cortona in the so-called Sala della Stufa and Planetary Rooms are among his best works.