The Fountain of Moses, also known as the Mostra dell’Acqua Felice, was built between 1585 and 1589 as the terminal of the aqueduct of the same name. The work was commissioned by Pope Sixtus V, who chose the name 'Felice' in homage to his own given name, Felice Peretti, as evidenced by the monumental inscription atop the attic.

The project, entrusted to architect Domenico Fontana, presents itself as an imposing triumphal arch with three niches, punctuated by four marble columns. The central niche houses the colossal statue of Moses, captured in the biblical moment when he points to the rock from which water will flow to quench the thirst of the Jewish people. Although the original rod has been lost, the hole that held it is still visible in his right hand.

A distinctive detail is the presence of horns on the prophet's head, due to a historical mistranslation of the Book of Exodus: the Hebrew term for the "rays of light" emitted from Moses' face was confused with the term for horns. The work, begun by Prospero Antichi and completed by Leonardo Sormani, was intended to rival Michelangelo's famous Moses (conserved in San Pietro in Vincoli). However, due to its massive proportions, it was harshly criticized by the Roman people, who ironically dubbed it the "ridiculous Moses." The statue also features a historical anachronism: Moses holds the Tablets of the Law, which he would, however, have received on Sinai only after the miracle of the waters.

In the side niches, two high reliefs celebrate other episodes related to water: on the left, Aaron leads the people towards the spring (sculpted by Giovan Battista della Porta); on the right, Gideon selects his soldiers by observing their drinking habits (sculpted by Pietro Paolo Olivieri and Flaminio Vacca).