Genoa lacked a public building until 1257 when the Captain of the people Guglielmo Boccanegra decided to build one at the Ripa Maris, the economic center of the time. The Antelami Magistri who arrived from Lombardy, under the guidance of the friar Oliviero, built the building as a pier stretching out towards the waves, but the palace was the seat of the Municipality for only 2 years, until, in 1262, Boccanegra was deposed and exiled. With the transfer of the city government to Palazzo Ducale, only the headquarters of the magistracies for controlling port traffic remained here and the customs and the "Compere" offices were established there, responsible for managing the money loans made by citizens to the Municipality. Tradition has it that here, after the Battle of Meloria, Marco Polo was held prisoner and dictated his Milione to the Pisan Rusticillo. In the 15th century
The palace passed to the Banco di S. Giorgio, a very powerful credit institution that managed the public debt of the Republic and administered the taxes and overseas colonies which expanded the building in 1570 and had Tavarone fresco the façade facing the sea with S. George slaying the dragon.
The most medieval part of the building with the 5-arched portico in gray stone, with three-light and four-light windows was restored and remodeled in 1890 by D'Andrade. Today it is the seat of the port authority and can be partially visited