After the fall of the Western Roman Empire, Porto Venere became the base of the Byzantine fleet in the northern Tyrrhenian Sea, but was destroyed by the Lombards in 643 AD. Later, it was a frequent target of Saracen raids. First indications of the existence of a castle date from 1113, and in 1161 the walls were erected. Porto Venere became a fiefdom of a family from Vezzano before passing to Genoa in the early 12th century. In 1494, it suffered a devastating bombardment from the Aragonese fleet during their war with Genoa: subsequently the old part of the town declined in importance, giving way to the development of the Borgo Nuovo ("New District"), which had existed from 1139 and is centred on the church of St. Peter. On 2 December 1797, after the French established their domination in Italy, the town became part of the Department of the Gulf of Venus, with the capital in La Spezia, in the Ligurian Republic annexed to the First French Empire. From 28 April 1798 with the new French law, the territory of Portovenere fell in the seventh canton, as the capital, the Jurisdiction of the Gulf of Venus since 1803 and the main center of the third State of the Gulf of Venus in the jurisdiction of the Gulf of Venus.