The former name of the piazza, Piazza dell'Esedra, still very common today, originates in the large exedra of the baths of Diocletian, which gives the piazza its shape.[1] The exedra present in the baths of Diocletian was incorporated into the gardens built by Cardinal Jean du Bellay; on his death in 1560, the land was purchased by Cardinal Carlo Borromeo, and eventually came into the possession of Cardinal Alessandro Sforza in 1579. Between 1598 and 1600 the exedra was converted into a church. Then, in 1885, the Via Nazionale cut through the centre of this structure.[2]
The porticos around the piazza, built in 1887–98 by Gaetano Koch, were in memory of the ancient buildings on the same sites, while the basilica of Santa Maria degli Angeli e dei Martiri on the piazza is based on a wing of the baths (with its architect Michelangelo, using the tepidarium as one of the wings of its spacious Greek cross plan).
Panorama of the Piazza Esedra (Piazza della Repubblica) from 1964 postcard
The naiads represented are the Nymph of the Lakes (recognisable by the swan she holds), the Nymph of the Rivers (stretched out on a monster of the rivers), the Nymph of the Oceans (riding a horse symbolising of the sea), and the Nymph of the Underground Waters (leaning over a mysterious dragon). In the centre is Rutelli's Glauco group (1911/12), symbolizing the dominion of the man over natural force and replacing a previous sculpture.