At the beginning the reign of Pope Sixtus V (born Felice Peretti) in 1585, only one of the ancient Roman aqueducts which brought water to the city, the Aqua Vergine, was still being maintained and working.

It featured, as ancient Roman fountains did, an inscription honoring its builder, Pope Sixtus, beneath angels holding the papal coat of arms.

The left bas-relief panel, sometimes referred to as a depiction of Aaron, and sculpted by Giovanni Battista della Porta,[6] may instead reflect either the miracles by Moses at Marah, where Moses removed the bitterness of the barely potable water of a spring in Sinai, or more likely the miracle at Masah and Meribah, where he struck the rock to cause water to flow (Exodus 17:5-7).

Finally, the bas-relief to the right sculpted by Flaminio Vacca and Pietro Paolo Olivieri, has been depicted as Joshua, but others claim the relief references Gideon in Judges 7:5, as evidenced by soldier's gear and animals lapping water.

[10] The statue of Moses was criticized at the time for its large size, not in proportion with the other statuary, but the fountain achieved its political purpose; it was a statement of how the Catholic Church, unlike the Protestant Reformation, was serving the needs of the people of Rome.