Although primarily interested in Italian painting, Gerbier also paused to admire the masterpieces of Greek and Roman sculpture. "Concerning Venus, there's not a figure in the world more genteel and more accomplished than that of Medicis at Rome, and next to that nothing more manly than the Hercules of Farnese, nothing more noble than the Apollo, the Meleager, the Gladiator, and above all the incomparable Laocoon, whereof the lineaments, the circular strokes, the muscles, the nerves, and the veins are so well expressed that it seems to be a gathering of figures petrified, and who in former times must have been of flesh, as the child at the town house at Sens in France, which a mother had borne sixteen years, and which was found in her body after death.”6 Perhaps Gerbier made many drawings of these antique statues. We know that he copied the Hercules in the Farnese Palace, and that it was so "excellently drawn with a silver pen upon a large piece of Table-book leaf" that it was "the admiration of all the Italians that saw it."7

In his determination to see Buckingham established in the finest private residence in Europe, Gerbier was indefatigable in visiting the palaces and villas of Rome - each an inhabited monument to the glory of a family. Setting the standard of magnificence for the future Keeper of York House were the "Palaces of Borghese, Oldebrandini, Guisi ... the Garden of Pleasure of the Cardinal Borghese, all beset with rare antique statues and within garnished with many rare pictures."8 The visit to the richly ornamented, suburban Villa Borghese called for a comparative study of the rival Villa Ludovisi that another papal-nephew, the Cardinal Ludovico Ludovisi, was constructing in his vineyards. Gerbier's love of magnificent building took him farther afield, to the towns of Frascati and Caprarola where the Roman aristocrats, the Aldobrandini and the Farnese, had their summer villas.

One of his favourites was the Palazzo de Chigi ("Guisi" in Gerbier's peculiar orthography) to which he returned again and again to study the frescoes by the divine Raphael. In company with other artists, he spent hours in the charming entrance hall overlooking the garden, copying the Banquet of the Gods. Working near Gerbier was a Florentine who explained that he was making sketches for a copy of monumental proportions. The finished work was to be in two parts, each nineteen feet long. Gerbier must have visited this artist's studio to see the work in progress because he purchased "the two great histories which are in making" for the sum of 42l, arranging for them to be sent to London on completion. Well satisfied with this transaction, he settled down to finish his own copy in coloured chalk. Gerbier’s copy found an enthusiastic admirer. "The best Crayons that ever I saw,” Edward Norgate later wrote in Miniatura, “were those made by Sr Balthazer Gerbier after those so celebrated Histories done by Raphaell of the banquets of the Gods, to be seen in the Pallazzo de Gigi."9 Norgate may have been somewhat prejudiced because he was a close friend of Gerbier’s and connected with him by marriage.