The Trevi Fountain is the show fountain of the Acqua Vergine; the Najadi Fountain is the show fountain of the Acqua Marcia; the Gianicolo Fountain, created between 1610 and 1614 to fulfil Pope Paolo V, Borghese request, is the show fountain of the Acqua Paola, fed by the Bracciano Lake after the restoration of the traianese aqueduct. Marble taken from the Foro was used in its construction while the six Ionic columns come from the ancient St. Peter's Basilica. The eagle and dragon carved in the gable are the heraldic symbols of the Borghese family.
The creation of this monument was commissioned to Giovanni Fontana from Ticino, designer of Palazzo Giustiniani, today home to the Senate, brother of the more famous Domenica whose works in Rome include the Palazzo del Laterano and the elevation of the obelisks in Piazza San Pietro, Piazza del Popolo, Piazza Santa Maria Maggiore and Piazza San Giovanni in Laterano.
Initially the water flowed into five small basins until 1690 when Pope Alessandro VIII, Ottoboni, had them replaced by a large white marble basin which can be admired today; in the same year the square was built in front of the fountain.
Gianicolo has always been considered important for Rome's defence because of its high position outside the pomerio, the sacred Urbe boundary, an ideal position to guarantee security. On this hill in 1849 Garibaldi, engaged in defensive action against the French troops called in by Pope Pio IX to combat the new-born Roman Republic, made his headquarters in the Casino Savorelli right next to the fountain.The Republicans, after two months of bloody fighting, surrended bringing an end to Mazzini, Armellini and Saffi's administration.
The story tells that during the siege the French troops cut off the city's water supply and during the hot hours of the day they sheltered from the sun by lying in the large basin of the shaded Fountain. The French general, Oudinot, having heard that the republicans intended climbing up the dry water pipes to get closer to him, gave an immediate order to reopen the water supply without warning; the water gushed into the Fountain drenching the Zouaves who were sleeping in the basin.
Goffredo Mameli dei Mannelli, author of the words of the national anthem, who accidently died from his wounds at the age of twenty two, is buried next to the Fountain together with other Garibaldians who sacrificed themselves for the Roman republic.
The inauguration of the Fountain by Paolo V inspired Pasquino with the following verses: «The miracle has been accomplished, o Holy Father,/ with your water, that you like so much;/ but it would be a much happier miracle/ if you could change the water into Orvieto wine.»