The Neptune figure was meant to be an allusion to the dominion of the Florentines over the sea. The figure happens to resemble the face of Cosimo I de' Medici. The figure stands on a high pedestal in the middle of an octagonal fountain. The pedestal in the middle is decorated with the mythical chained figures of Scylla and Charybdis.

The center statue is of Neptune, standing atop a rock as he fights a sea monster. Near him at the edge of the fountain sits two Naiads, one on each side. One is smiling as she wraps herself around a swan that is gushing water out its mouth, while the other is scowling as she hangs onto the tail of another sea monster. Water sprays from her mouth. Two seahorses are placed in between. One is meekly being led by a happy child while the other is wild, trying to rid itself of its rider. Several other smaller statues of imps adorn the fountain. One is playing with a crab, one has a shell, one is fighting with a sea monster and another is trying to climb onto a dolphin.

Accordingly, the statue of Neptune is only a copy made in the nineteenth century. The original is now in the National Museum.

Thewater fountain has suffered a great deal of damage during the centuries. It was used as a washbasin for laundry at the end of the 16th century and vandalized on January 25 1580. A satyr was stolen during the carnival in 1830. It was damaged again by the Bourbon bombardments of 1848. As a result, it has been the object of several restorations and substitutions. On August 4 2005, the statue was the target of three vandals who climbed it, damaging one of the hands and the trident of Neptune. The act was recorded by security cameras. The statue was restored on 2007.