The Fountain of Neptune in Bologna was completely designed, with the exception of Neptune himself, by Tommaso Laureti. Painter, engineer and sculptor from Palermo, he designed and planned the whole structure of the fountain, from its external decorations to the tubes that even nowadays connect the fountain to the cistern on the hills, also designed by Laureti, called the Cistern of Valverde.
The architect was inspired by the fountains he had seen all around Rome. Unfortunately, he did not take into account the fact that the water in Bologna had a higher concentration of limescale than the one in Rome. He paid dearly for his mistake as his cistern never worked at a full capacity and neither did his fountain, where only some of its nozzles sprinkled water.
The original design placed the fountain in the middle of Piazza Maggiore. Yet, considering the square was a central meeting point for citizen events and therefore a too dangerous place for such a delicate piece, a new protected corner was made for the fountain by demolishing some buildings and creating the now called Piazza del Nettuno (Square of the Neptune).
The base of the fountain is decorated by four Latin sentences that recall its genesis: "aere publico" meaning built with the citizens money, "popoli commodo" which reminds us of its service to the people of Bologna, "fori ornamento" concerning the decorative function of the fountain and the fourth inscription with the date of its construction, 1563.
On the center of its second level we can see the different coats of arms of main characters of those years: the characteristic “six balls in orle gules” of Pope Pius IV, the coat of arms of Pier Donato Cesi and on the opposite side from the Pope’s, the coat of arms of Carlo Borromeo. Inside Borromeo’s coat of arms we see the representation of two horse bits. The original bits, currently preserved in the Cathedral of Milan, were said to be built with the original nails from the crucifixion and held by Saint Borromeo presumed to cure the plague that was troubling the city.
The four cherubs that decorate the corners of the fountain hold dolphins in their hands, symbolizing the 4 main rivers in the world: the Ganges, the Nile, the Amazon River and the Danube, while the so-called sirens at its base are in fact Nereids, two-tailed sea nymphs.
The sensuality of the Nereids caused a great turmoil during the years following its inauguration. The application of the rules by the Council of Trent in 1563 and the aim for a higher morality had as a result the censoring of art pieces (we may recall that this was the period in which trousers were painted in the Sistine Chapel) and the Nereids were considered outrageous. Apparently, young ladies from good Catholic families in Bologna avoided passing in front of them when reaching into the main square.