The fountain constitutes the terminal fountain of the Acqua Vergine, the aqueduct built by Agrippa – general, son in law and collaborator of Augustus – to feed his thermae at the Pantheon, inaugurated in 19 BC. According to a legend handed on by Plinius the Elder and by Frontinus, the name of the aqueduct comes from a young girl (virgo), who indicated the location of the spring to Agrippa’s soldiers. 

Seriously damaged by the Goths in 537 and restored a first time in 790, the restoration of the aqueduct was commissioned in 1453 by Nicholas the Fifth Parentucelli (1447-1455) to Leon Battista Alberti and Bernardo Rossellino. On this occasion a new fountain was built and restored by Giacomo della Porta in 1563. 

It consisted of a rectangular pond leaning against a supporting wall that bore an inscription with the coats of arms of Nicholas the Fifth and of the Municipality. A new fountain was commissioned to Gian Lorenzo Bernini in 1640 by Urban the Eighth Barberini (1623-1644). 

The projects presented by Bernini were not carried out, probably due to the high costs, but it was decided all the same to change the orientation of the fountain that was turned towards Piazza dei Crociferi. Bernini built two concentric circular ponds, leaning against a concave exedra. A long wash-tub that was next to the fountain was moved later to Piazza del Lavatore. At this point the works were interrupted due to the high costs incurred by the papacy for the war against Castro. 

After various projects that were never carried out, the fountain was finally rebuilt in 1732 under Clement the Twelfth Corsini (1730-1740) according to a project by Nicola Salvi. The works were continued by Giuseppe Pannini after Salvi’s death (1751) and lasted until 1762, when the fountain was finally inaugurated by Clement the Thirteenth Rezzonico (1758-1769). Pannini made changes to Salvi’s original project, the most important of which consists of the three basins below the statue of Ocean sculpted by Pietro Bracci. 

The fountain leans against Palazzo Poli that was enlarged between 1728 and 1730 just to allow placing the new fountain, and was lowered in comparison with the square due to the low level of the Acqua Vergine. An attic with a balustrade and allegoric figures is centered above the triumphal arch. It represents from left to right: Abundance of fruits, Fertility, Wealth and Amenity with their attributes. 

A large inscription in the centre bears the papal coat of arms supported by two winged figures, the Fames, to commemorate the completion of the opera commissioned by Clement the Twelfth Corsini. The side parts of the facade present windows separated by pilasters. The statue of Ocean on a shell-shaped coach pulled by two seahorses driven by tritons is placed in the large central niche with a lacunar ceiling. The statues of Healthiness and, on the left, of Abundance by Filippo della Valle are located in the side niches. 

Above these two panels in relief represent the Virgin indicating the spring to the soldiers (on the right), and Agrippa ordering the building of the aqueduct and approving its design (on the left). An imposing naturalistically sculpted cliff engraved with plants and animals, constitutes the base of the facade of the building and the water flows on it from various openings, contributing with the sculptures to the monumentality of the most famous fountain in the world. 

By tradition the tourist that tosses a coin in the fountain will certainly come back to Rome.