The building, starting from 1610, of the last Roman aqueduct, the Acqua Paola, didn't move to the background the two aqueducts built just a few years before (the Aqua Virgo in 1570 and the Acqua Felice in 1586), which gave the possibility to erect new fountains on the branches that guaranteed a more widespread distribution of water in the whole town.

A secondary branch of the Acqua Felice reached the area south of the Tiber Island: here, between ancient and middle-age monuments (the Arcus Argentariorum, the Arch of Janus, the Temple of Hercules Victor, the Temple of Portunus and the basilica of Santa Maria in Cosmedin).

It is not clear why the pontiff chose to erect a fountain in an area that was scarcely inhabited, broken-grounded and subject to the floods of the Tiber.

The whole travertine structure is placed on a circular step (delimited by 16 little columns joined by a grating), within which the design of the main basin represents an octagon with concave sides, or rather the eight-tips star that was the heraldic symbol of the family of the Pope, the Albanis).

[1] In the centre there is a group of rocks (an element that had become popular after the success of the fontana dei Quattro Fiumi) with bushes on which two Tritons, sculpted by Francesco Moratti, kneel with entwined tails and raised arms, sustaining on their shoulders a big oyster shell serving as upper basin.