The naval Battle of Giglio was a military clash between a fleet of the Holy Roman Emperor Frederick II and a fleet of the Republic of Genoa in the Tyrrhenian Sea. It took place on Friday, May 3, 1241 between the islands of Montecristo and Giglio in the Tuscan Archipelago and ended with the victory of the Imperial fleet.

Pisa is a city and comune in Tuscany, central Italy, straddling the Arno just before it empties into the Ligurian Sea. It is the capital city of the Province of Pisa. Although Pisa is known worldwide for its leaning tower, the city contains more than twenty other historic churches, several medieval palaces, and bridges across the Arno. Much of the city's architecture was financed from its history as one of the Italian maritime republics.