Here in ancient Rome there was a stadium built by Domitian, whose arena was 276m long and 54m wide, and later restored by Emperor Septimius Severus.
Today it is one of the most characteristical squares in Rome thanks to its pedestrian precint, the three existing fountains (fountain of the four rivers, fountain of the moor, fountain of Neptune) and to the church of S.Agnes.

Fountain of the four rivers
Pope Innocence X Pamphilj authorized work on the removal of the obelisk from the Circo Massenzio, the 12th of June 1851, and its placement in Piazza Navona, according to Bernini's project. Around this monolinth were placed four white marble statues, five metres tall which represented rivers.
The first was by Claude Poussin and was dedicated to the Ganges, symbolising Asia; the Nile, representing Africa, was carved by Giacomo Antonio Fancelli, its veiled head standing for the up till then unknown source of the river, the Danube for Europe, carved by Antonio Raggi and finally the Rio de la Plata, representing America by Francesco Baratta.
Works ended in 1878


Fountain of the moor
This fountain, erected in 1574 following the plans of Giacomo della Porta during the reign of Pope Gregory XIII Boncompagni, was completely restored in 1653 by Bernini who had received orders from Pope Innocence X Pamphilj. During the restoration of 1874 the four Tritons and the four masks were substituted with copies by Luigi Amici (the originals may be found in Municipal deposits). The central sculpture, designed by Bernini and carved by Giannantonio Mari in 1655, is mistakenly called "The Moor" due to its characteristic facial features but is really a muscular Triton who is riding a dolphin.


Fountain of Neptune
This fountain, placed in the northern part of the square, was also restored by Bernini but remained for three hundred years without statues and decorations.
In 1873 Antonio Della Bitta won the competition to carve the statue of Neptune, whilst Gregorio Zappalà carved the group around the basin: sea-horses, mermaids and putti playing with the dolphins.