Fontana del Nettuno, Piazza del Popolo, Classical fountain in Piazza del Popolo, Italy.

The Fontana del Nettuno stands on the west side of Piazza del Popolo, where the Acqua Vergine Nuovo aqueduct ends. Giovanni Ceccarini designed it in 1822–23: Neptune holds his trident, flanked by two Tritons.

The fountain was designed and built by Giuseppe Valadier and Giovanni Ceccarini in 1823 as part of the Piazza del Popolo redevelopment. Water for it comes from the Acqua Vergine Nuovo aqueduct, which terminates at this basin.

The fountain's name comes from the sea god it depicts: Neptune holds a trident, flanked by two Tritons, the merman messengers of the sea. The group was carved by Giovanni Ceccarini, whose fountains also stand elsewhere on the square, so the same hand shaped the piazza's water displays.

The fountain stands on the west side of Piazza del Popolo, where the Acqua Vergine Nuovo aqueduct ends; the square opens off Via del Corso, Via di Ripetta and Via del Babuino. Approach from the east side of the square for a frontal view of Neptune and the two Tritons.

The fountain marks the terminus of the Acqua Vergine Nuovo, the aqueduct built to supply this part of Rome; water reaches the basin from that new line rather than from the ancient Acqua Vergine. Giovanni Ceccarini designed the fountains of the square, and this one stands on its west side, facing Neptune and his two Tritons.