It was, in fact, inaugurated in a provisional form by the pontiff on 10 September 1870 in the Termini area, in the place currently occupied by the Dogali obelisk (erected in 1888) and built in a definitive form only after the establishment of the unitary state, in the current Piazza della Repubblica, the cornerstone of the new urban structure of the capital.

The architectural part was built in 1885 based on a design by Alessandro Guerrieri according to the directives of the building commission which also included plastic decoration. The fountain was then temporarily decorated with four stucco lions on the occasion of the visit of Emperor Wilhelm II in 1888.

Finally, in 1897, Mario Rutelli (1859 – 1941) was entrusted with the task of creating the sculptural part. The artist created the bronze sculptures that made the work known as the "Fountain of the Najadi": four groups composed of nymphs, animals and aquatic monsters, extremely vital and joyful female figures almost intent on playing with animals and monsters that ride under the splashes of water.

The fountain was inaugurated in 1901 and only later was completed by Rutelli with a central group; the work, temporarily created in concrete in 1911, was not considered suitable and in 1913 it was transferred to the garden in Piazza Vittorio Emanuele II. In its place Rutelli placed the powerful figure of Glaucus entwined with the dolphin from whose mouth the central jet of water releases very high. Inaugurated in 1914, the fountain constitutes the most significant example of the liberty language in Rome and the expression of the desire of the unitary state to insert itself with a new language into the tradition of exhibition fountains.

At the base of the niches the water flows from a fake cipollino marble cliff into the basins originally decorated with four ancient lions in porphyry and marble from the Pantheon and the Lateran respectively, replaced in 1850 with others in bardiglio marble, made by Adamo Tadolini (1788-1868). The fountain is surrounded at the base by a travertine balustrade, created at the time of Pius IV (1559-1565) for the Belvedere courtyard in the Vatican and reused here.

Above the columns runs a cornice which shows the dates of construction of the work (1585-1587) and the very high attic in which the long commemorative inscription is located surmounted by the papal coat of arms supported by two angels. The construction is completed by a gilded copper cross, an element present in all the "notable factories" built by Sixtus V.

marine, the Triton stands imposingly with his head bent backwards in an effort to blow into the large whelk (or twisted shell) which he supports with his arms raised upwards and from which copious water flows out and sprays the entire work. Expression of the new baroque concept of space, in the fountain the sculptural part includes and completely absorbs the same architectural structure: the shell on which the triton rests constitutes the upper basin of the fountain, and the balustrade at the base is replaced by four dolphins with intertwined tails, between which are placed the papal coats of arms with bees, the heraldic symbol of the Barberini family.

Bernini himself was also responsible for the design of a fountain for the use of wayfarers originally located in the square, on the corner with Via Sistina, known as the Fontana delle Api (today at the beginning of Via Veneto).

it was a collaboration. Pietro Bernini designed an absolutely new fountain compared to the works created in Rome at the end of the 16th century; in fact, he was inspired by a boat, creating a work that was more sculptural than architectural. The unique boat-shaped basin collects the water that comes out of two large suns - located inside the hull at the bow and stern - and that which gushes from a small central basin. The water overflowing from the sides of the boat, open so as to give the impression that it is sinking, is collected by an underlying basin into which the jets coming from the mouths of fake gunboats located outside the bow and stern, on the sides of the large papal coats of arms characterized by bees, symbol of the Barberini family, also flow.

In 1640 by will of Pope Urban VIII (1622-1644), in conjunction with the expansion of the square, Gian Lorenzo Bernini designed a new fountain oriented like the current one, the construction of which was limited to the installation of an exedra base with a basin in front, placed against the buildings later incorporated into the Poli palace.

The creation of the current Trevi fountain is due to Pope Clement XII (1730-1740), who in 1732 announced a competition in which the major artists of the time participated. The pontiff chooses among the projects of the architect Nicola Salvi (1697-1751) the most monumental and "of least harm to the palace behind" on whose façade the entire exhibition is placed with a thoughtful study of the proportions and decorations.

The fountain, structured like a triumphal arch, with a deep niche, slopes down towards the large basin with a large cliff, brought to life by the sculptural representation of numerous plants and the spectacular flow of the water. In the center dominates the statue of Oceanus driving the shell-shaped chariot, pulled by the angry horse and the placid horse, braked by two tritons. Reliefs that allude to the history of the aqueduct and allegorical figures connected to the beneficial effects of water decorate the façade at various levels. History and nature, understood in a dialectical relationship, as affirmed by the nascent Enlightenment, thus masterfully merge in Salvi's work.

The construction was completed by Giuseppe Pannini (c.1720-c.1810) who partially modified the cliff by regularizing the central basins.

After a restoration intervention in the years 1989-1991 (this was followed by maintenance of the central part in 1999), in 2014 thanks to FENDI, the last intervention was carried out at the end of 2024. This activity was placed in an intermediate position between the ordinary cleaning and maintenance operations which are periodically carried out with the emptying of the tanks and the structural restoration interventions (such as those of 1989-90, 1999 and 2014) aimed at eliminating limescale and biological patinas that deposit on the materials.

In 1711, by will of Pope Clemente The obelisk of Ramses II stands on a fake travertine cliff, on which is inserted a plinth decorated on the corners with dolphins, while on two faces of the same plinth two monumental Alban coats of arms are sculpted. On the other faces an epigraph celebrating the interventions of Clement XI is repeated. At the base of the plinth there are inscriptions relating to the restorations.

During the restoration of 1880, the original masks (in storage at the Museum of Rome) were replaced by nineteenth-century copies by Luigi Amici (1817–1897).

In 1647 the pontiff entrusted Francesco Borromini (1599 – 1667) with the project of the new pipeline which was to bring 180 ounces of the Virgin water to Piazza Navona and, at the same time, decided to transfer the obelisk (a Roman copy from the Domitian era) to the square which was lying in pieces in the area of ​​the circus of Maxentius on the ancient Appian Way.

After completing a competition of ideas in which important artists of the time participated, the pope entrusted the task of creating the work to Gian Lorenzo Bernini, who had presented a silver model of the new fountain
At the center of a low elliptical basin, the fountain is imagined as a large travertine cliff, dug by a cave with four openings, which supports the granite obelisk.  On the corners of the cliff are placed the monumental marble statues of the four rivers representing the continents known at the time, also identified by the vegetation and animals sculpted next to them: the Danube by Antonio Ercole Raggi for Europe, with the horse; the Ganges by Claude Poussin for Asia, with the oar and the dragon; the Nile by Giacomo Antonio Fancelli for Africa, with the veiled head (allusion to the unknown sources) associated with the lion and the palm tree; the Rio della Plata by Francesco Baratta for America with one arm raised - perhaps to protect himself from the rays of the sun represented by the obelisk - and next to an armadillo.Sulla parte alta della scogliera sono due grandi stemmi marmorei della famiglia del papa con la colomba che porta nel becco un ramo di ulivo, e la stessa colomba, in bronzo, è collocata alla sommità dell’obelisco.
The fountain was built between 1648 and 1651 by a large group of artists and workers directed by Gian Lorenzo Bernini.
A masterful fusion of architecture and sculpture, the Four Rivers fountain expresses movement in every sculptural detail, from the vegetation, to the statues, to the fauna represented in the basin and on the cliff, becoming the fulcrum of the entire surrounding space.

Following the restoration of the ancient Vergine aqueduct, it was decided already in 1570 to install a fountain in the nearby Piazza Giudea; however, the insistence of the noble Muzio Mattei had induced the Administration to move the fountain to the current square overlooked by his private residence. The same nobleman, who undertook "to have the square bricked at his own expense and keep the source clear", must also have been no stranger to the choice, made during construction, to replace the project's marble with bronze in the creation of the sculptures.

The four turtles placed on the edge of the upper basin, attributed by tradition to G.L. Bernini, constitute a happy completion of the work carried out during the restoration of 1658-59, under the pontificate of Alexander VII (1655-1667), remembered on the inscriptions of the four marble cartouches.

Designed on the model of the ancient triumphal arch, the fountain consists of five large arches flanked by columns and a large attic with the dedicatory inscription. For the decorative part, white and polychrome stripped marbles were used, coming from the Roman Forum and the Temple of Minerva at the Forum of Nerva, while the columns, in red and gray granite, belonged to the ancient Constantinian basilica of St. Peter.
At the end of the 1600s the architect Carlo Fontana (1638-1714) modified the façade, giving the fountain its current shape: a monumental marble basin was added to replace the five collection basins, originally inserted between the intercolumns of the arches.

Damaged by French cannons during the short Roman Republic of 1849, the fountain underwent a first restoration in 1859 and subsequently in 1934 and in the 1950s. The last important conservative intervention carried out by the Capitoline Administration dates back to 2002-2004.
From 1901 to the 1930s, the water from the "fountain" powered Rome's first hydroelectric power station.
A curiosity: the large, and beautiful, epigraph in the attic contains an error. In fact, the restoration of the Alsietino aqueduct is mentioned while in reality, as we have seen, it was the ancient aqua traiana that was restored.

Behind the fountain there is a small garden in memory of the much larger one that existed in the seventeenth century and which Pope Alexander VII Chigi (1655-1667) had designated as a Botanical Garden. The small garden at the back of the monument is accessed via a staircase in via Garibaldi n. 30, from where you can enjoy a magnificent panoramic view of the city.