On the walls are one-and-twenty representations of scenes in Venetian history devoted to the exploits of the two Doges, Sebastiano Ziani (1172-1178) and Enrico Dandolo (1192-1205). The greatest moment in the career of Ziani was the meeting of Barbarossa and the Pope, Alexander III, at S. Mark's, which has already been described; but his reign was eventful throughout. His first act as Doge was to punish the assassination of his predecessor, Vitale Michiel, who, for what was held to be the bad management of an Eastern campaign which utterly and disastrously failed, and for other reasons, was killed by the mob outside S. Zaccaria. To him succeeded Ziani and the close of the long feud between the Pope and the Emperor. It was the Pope's sojourn in Venice and his pleasure in the Venetians' hospitality which led to the elaboration of the ceremony of espousing the Adriatic. The Pope gave Ziani a consecrated ring with which to wed his bride, and much splendour was added to the pageant; while Ziani, on his return from a visit to the Pope at the Vatican, where the reconciliation with Barbarossa made it possible for the Pontiff to be at ease again, brought with him various pompous insignia that enormously increased his prestige among simple folk. It was also Ziani who had the columns of S. Theodore and the Lion erected on the Molo, while it was in his reign that the first Rialto bridge was begun. Having been Doge for six years, he retired to the monastery of S. Giorgio and there died some years later, leaving a large fortune to the poor of Venice and the church of S. Mark. The paintings represent the Pope Alexander III recognized by the Doge when hiding in Venice; the departure of the Papal and Venetian Ambassadors for Pavia to interview the Emperor; the Pope presenting the Doge with a blessed candle; the Ambassadors before the Emperor (by Tintoretto); the Pope presenting the Doge with a sword, on the Molo; the Pope blessing the Doge; the naval battle of Salvatore, in which the Emperor Otto was captured; the Doge presenting Otto to the Pope; the Pope giving Otto his liberty; the Emperor at the Pope's feet in the vestibule of S. Mark's; the arrival of the Pope elsewhere; the Emperor and the Doge at Ancona; the Pope presenting the Doge with gifts in Rome. [Illustration: THE CORNER OF THE OLD LIBRARY AND THE DOGES' PALACE]