As Zuccari correctly noted, this is a study for Nebbia´s lunette fresco of the Donation of Constantine painted in the Benediction Loggia of S. Giovanni in Laterano, Rome, in c. 1590 (Madonna, 1993, p. 124). Nebbia and his collaborator, Giovanni Guerra (1544-1618) organized the decoration of the loggia, which was shared between a number of other painters. Payments to Nebbia and Guerra for their work there, as well as for their share in the decoration of the first floor of the Lateran Palace, are recorded in 1588-1589 (Gere and Pouncey, 1983, p. 132; R. Torchetti in Madonna, 1993, pp. 122-125). Four other drawings by Nebbia for the Loggia are known: Pierpont Morgan Library NewYork; Louvre; Museu de Arte Antiga, Lisbon (Cambridge, Lisbon and elsewhere, 2000-01, p. 297, no. 69); and in a private collection, London; furthermore, there is a study for a female allegorical figure by Guerra in the Kupferstichkabinett, Staatliche Museen, Berlin (Eital-Porter, 1997, chapter VIII, 3).

The Roman emperor Constantine the Great (c. 280-337) converted to Christianity on the eve of the Battle of Milvian Bridge in 312, when he defeated the emperor Maxentius. According to tradition, one of Constantine´s decrees as the newly crowned Emperor was to donate the lands of Central Italy, including Rome, to Pope Sylvester (314-335) and to give him primacy over other bishops. In the Prado drawing, Constantine kneels at an altar in the center of the composition and reads from the deed of his donation, which he holds in front of him at the altar. Seated on a throne beside the altar, to the left, is Sylvester, his hands raised in prayer. Commemoration of Constantine´s Donation within the Lateran Basilica -the cathedral of Rome- would have had a particular significance, for it is constructed on ground that Constantine gave to the Roman Church expressly for the purpose. The Lateran property comprised not only the ancient garrison of the Equites Singulares, over which the basilica is indeed built, but also much of the surrounding land.

On the verso are three studies for the figure of the youth, who leans forward into the picture space to peer at the emperor, his back turned to the spectator. The figure´s primary function is to lead the spectator´s eye into space across the line of his back; but at the same time he is a somewhat irreverent distraction from the central focus of the composition. The artist evidently had trouble deciding on the size and position of this figure, not daring to make it too prominent in so important a composition.

Nebbia was a tireless purveyor of pictorial inventions at a time of rocketing demand for interior decorations that would seem worthy of the fine exteriors to the many magnificent buildings then being erected in Rome. At the end of the sixteenth century under the aegis of such popes as Gregory XIII (1572-1585) and Sixtus V (1585-1590) and thanks to the new spiritual climate brought about by the Counter Reformation, the Holy City was expanding rapidly according to revolutionary new principles of urban design. Nebbia was one of the many artists of the time who benefited from this great spurt in artistic patronage. His work as a painter is in the mould of the Zuccari, though it is less exuberant than that of Giovanni de´ Vecchi, who was from the same milieu but who did not enjoy the same high degree of official favor. As to Nebbia´s style of drawing, this too is in the same Zuccaresque vein, but more methodical and routine (Text drawn from Turner, N.: From Michelangelo to Annibale Carracci. A century of Italian drawings from the Prado, Art Services International-Museo Nacional del Prado, 2008, p. 126).