The spring and shrine of Juturna (Lacus Juturna) is situated immediately to the east of the Temple of the Dioscuri (Castor and Pollux), south-west of the Atrium Vestae and north of the Palatine. The cultic complex comprises of a natural water spring, a Roman period pool with a pedestal, and an aedicula with an altar.

circa 700/600 BCE-

The cultic precinct of Lacus Juturna dates back to the archaic period (circa 6th century BCE). According to the legend, Castor and Pollux, the divine twin horsemen who led Rome to victory over the Latins(Ionian Revolt of 449 BCE), were seen here watering their horses. Later on a temple was dedicated which later came to be known as the Temple of Castor and Pollux. The fountain over the natural spring was rebuilt several times between the 200 and 100 BCE. Then again, during the Imperial period; it was remodelled and cladded in marble. After the fire of 283 CE, the shrine, itself, was rebuilt using the original architectural elements. A small pedestal was installed in the center of the basin which held the statues of the Dioscuri. Today an ancient altar depicting the twins (Castor and Pollux; dioscuri) is preserved and placed on this pedestal. The statues of the dioscuri were discovered in fragmentary condition.

The real value of these finds consists, however, simply in the fact that they bear eloquent testimony that Greek myths once adopted by Rome rose quickly into the position of dogmas.

circa 700/600 BCE

Aedicula and the Altar
The shrine dedicated to Juturna was constructed in the form of an aedicule, and today stands adjacent to the "Oratory of the 40 Martyrs". Inside the apsidal cella was a cult statue of Juturna, the goddess of wells, springs, and fountains. The nymph, an ancient but lesser deity, and the waters over which she presided were thought to give nourishment and health. The architrave bears aninscription that reads: IVTVRNAE S. The shrine sits on a high pediment with no approaching stairs and two slender Corinthian columns framing a shallow porch. The peculiar orientation, oblique to other nearby buildings, is due to its alignment with the Regia and the House of the Vestal Virgins, before it was rebuilt after the fire of 64 CE.

The wellhead (inspect) dating back to the Augutan period (circa 27 BCE- 14 CE) bears an inscription commemorating a first-century BCE restoration by Marcus Barbatius Pollio, the curule aedile responsible for the maintenance of public buildings. The marble well in front has a double inscription with the name of Marcus Barbatius Pollio, curule aedile, who lived in the Caesarian-Augustan era.

circa 700/600 BCE

Fountain or Spring of Juturna
The water collection basin, fed by two springs in the northern corners, is approximately square (5mx5m), covered in marble and with a rectangular pedestal in the centre. At a depth of approx. a meter, on the pavement of the Augustan era, is the lower basin of the Republican era, built in almost reticulated work, typical of the period between the end of the 2nd and the beginning of the 1st century BCE. The most accepted dating is that connected to the restoration of the nearby temple of the Castor and Pollux by Lucius Cecilius Metellus Dalmaticus in 117 BCE. Later restorations can be seen there, probably from the beginning of the imperial phase, in different tuff, datable to the restoration of the temple in the Tiberian era (14-37 CE).

In the basin were found the statues of the Dioscuri broken into pieces, originally placed, most likely, on the central pedestal and today preserved in the museum of the Roman Forum together with the statues of Apollo and Aesculapius, which decorated the fountain. They depicted the Dioscuri in the act of watering their horses at the fountain, as in their legendary appearance in the Forum before the victorious battle of Lake Regillus faught circa 496 BCE.

These are works in archaic style, typical of the late Hellenistic age, contemporary with the end of the 2nd century BCE. They were probably damaged in the fire of 12 BCE, as demonstrated by the restorations in different marble (Carrara marble instead of Pentelic marble) and the traces of fire. The relief seen today on the pedestal of the fountain is a copy (the original is in the Antiquarium) of a Trajan relief with the Dioscuri, their parents Jupiter and Leda and Juturna.

The altar dates back to the time of Septimius Severus, and features various representations: on the larger sides, those of Juturna and Turnus and the Dioscuri, on the smaller sides Jupiter with a sceptre and thunderbolt, and Leda with the swan.

Undated

Statio Aquarum
An inscription from the early fourth-century CE on the base of a statue dedicated to Constantine by the curator aquarum suggests that the site by then had become headquarters for the Statio Aquarum (water board of Rome), the office having been transferred after the fire of 283 CE from the Campus Martius (sacred area of ​​Largo Argentina), where there is a Temple to Juturna (Servius, XII.139). Or it may be that the Lacus Juturnae simply was the cult site for dedications of the curatores.