Emperor Frederick I. doing homage to pope Alexander IIIPeace of Venice (or Treaty of Venice)(Paix de Venise ou Trait?de Venise) between Pope Alexander III (pape Alexandre III) and Frederick I; Holy Roman Emperor (Frederick Barbarossa - Frederic Barberousse) on July 24; 1177. by Francesco Salviati (1510-1563) and Giuseppe Porta also known as Giuseppe Salviati (1520-1575)Painting at the Regia Hall (Sala Regia - salle royale) in the Apostolic Palace (Palais Apostolique) at the Vatican (2018)