Focus on The Tribuna of the Uffizi (Zoffany) and explain the Artworks shown.
Zoffany's picture is not a historical record of the works displayed in the tribuna in the 1770s. Rather, it is an epitome of the works in the Medici collections he felt to be most important. To accomplish that goal, several works from other rooms in the Uffizi and seven paintings from the Galleria Palatina in the Palazzo Pitti were transferred to the Tribuna. To accomplish this, Zoffany requested the assistance of  George, 3rd Earl Cowper, who had emigrated to Florence and Sir Horace Mann, who served as British diplomatic representative in Florence to the Grand Dukes of Tuscany. Two pictures by Raphael which Earl Cowper owned and hoped to sell to George III, and the Earl are depicted in Zoffany's painting. The unframed Samian Sibyl on the floor, acquired for the Medici collection in 1777, was a pendant to Guercino's Libyan Sibyl, recently bought by George III, and its inclusion may have been intended as a compliment to him.
George, 3rd Earl Cowper George III Raphael Guercino Tribuna Florence Sir Horace Mann Grand Dukes of Tuscany Uffizi British Libyan Sibyl