Fontana di piazzetta San Simeone, Renaissance fountain in Piazzetta San Simeone, Rome, Italy.

Fontana di piazzetta San Simeone is a small fountain with a round lower basin bearing the coats of arms of the three Conservatori and the Priore dei Caporioni, added in 1829. Above it, a baluster resting on a cube carries a smaller upper basin with a central jet, and four grotesque masks on that support spout water from their mouths. It stands on a circular pavement edged by small posts joined by an iron railing.

The fountain was designed by Giacomo della Porta in 1589 and originally stood in Piazza Montanara near the Teatro di Marcello. It was relocated twice, first to Giardino degli Aranci in 1932 and then to its current location in 1973.

The four grotesque masks on the upper support, added in 1696, spout water into the lower basin; the nuns of a nearby monastery paid for the work and in exchange gained the right to use part of the water. The lower basin carries the coats of arms of the three Conservatori and the Priore dei Caporioni in office in 1829, identified by the archaeologist Carlo Pietrangeli — one of the city's most representative examples of magistrates' emblems on a public monument.

The fountain stands on a circular raised pavement edged by short pillars joined by an iron railing, in the small piazzetta di San Simeone just off Via dei Coronari. It is reached on foot through the narrow streets of the Ponte rione. The fountain is currently awaiting restoration, so water may not be flowing.

The lower basin underwent renovation in 1829 and received newly carved emblems of the Conservatori and Priore dei Caporioni along its edges. These decorative additions remain visible today and show how important Roman institutions marked their authority through public works.