Genoa was founded by Ligurian tribes. Thanks to its position on the sea, Genoa created commercial relationships with Greeks and Phoenicians.

During the Second Punic War Genoa was linked to Rome by a foedus aequum, in fact Roman army used Genoa to reach Padana Plain and fight against Hannibal. His brother Magone destroyed and sacked Genoa. Genoa was rebuilt in 203 b.C. as an order by proconsul Spurio Lucrezio. After having defeated Carthage, Rome wanted to conquer Northern territories and used Genoa as a base to enter the Northern regions, inhabited by Ligurian tribes, allied to Carthage (between 191 and 154 b.C.). At the beginning of IV century a.C., Rome started to decline and Milan, instead, started to become more and more important. Genoa took advantage from this situation to improve its strategic role.

With the Crusades, Genoa started the colonization. Commercial routes were now towards Eastern countries. Genoa contributed to the conquest of many towns in the Holy Land, such as Jerusalem. There is a very famous episode about the Crusades. Captain Guglielmo Embriaco with a mobile tower scrambled up the walls of the town and incited the Christian soldiers to do the same.

Genoa was declared a free municipality by Emperor Fredrick Redbeard, and strong walls were immediately built to protect the town. Genoa became more and more important after the victory of Meloria against Pisa (1284) and that of Curzola against Venice (1298).

In Genoa there was the creation of the first world modern credit institute, Banco di San Giorgio, that soon became very powerful managing overseas territories.

Genoa was affected by the conquest of Constantinople by Turks. Many explorers came from Genoa: they worked for the republic itself or often for other monarchs. The most famous explorer was Christopher Columbus, who discovered the "nuevo mundo" (the new world).

In 1528 admiral Andrea Doria allied to Spanish Emperor Charles V and started the so-called golden century for Genoa. When Louis XIV conquered Genoa in 1684, he involved the town in the fights of French reign against Austria. Austrian army conquered Genoa in 1746. The town freed itself thanks to a popular rebellion and remained an aristocratic republic until 1797. After Napoleonic period, in 1815 European powers decided to suppress the republic and to annex the territories to the Reign of Sardinia (they had strong debts towards the ancient Banco di San Giorgio).

Genoa gave great people to Italian Risorgimento: Giuseppe Mazzini, Goffredo Mameli, Nino Bixio.

The famous Expedition of the Thousand led by Giuseppe Garibaldi left from Genoa and it was the most important step leading to the creation of the Reign of Italy. In 1892 the congress that led to the creation of Italian Socialist Party took place in Genoa.