The palace was built in 1260 by Guglielmo Boccanegra, uncle of Simone Boccanegra, the first Doge of Genoa. For the construction of the new palace, materials were used from the demolition of the Venetian embassy in Constantinople, having been obtained from Byzantine Emperor Michael VIII as a reward for Genoese aid against the Latin Empire. Stone lions, the emblem of Venice's patron St. Mark were displayed as trophies on the facade by her bitter rival, the Republic of Genoa. The palace was intended through the creation of a civil-political center to separate and elevate the temporal power of the Republic's government from the religious power of the clergy, centered on the Cathedral of San Lorenzo. The palace was used for a time as a prison; Marco Polo was its most famous resident and it was there that he dictated his memoirs to Rustichello of Pisa. In 1407, the palace became home to the Bank of Saint George (Casa delle Compere di San Giorgio, a trading company and bank), which was closed by Napoleon in 1805. The frescoes of the 1570 wing facade were repainted in 1990.