This beautiful 19th century square till the WWII was an official entrance to the city and its principal center of representation. Starting from the middle of the 17th century in the zone of Terme di Diocleziano (Baths of Diocletian), popularly denominated "Termini", a meat market took place every Thursday and Friday, transferred here from Campo Vaccino, and in the month of May a fair of horses and donkeys occurred here as well. At present the square bears an official name "Piazza della Repubblica", but Romans call it Piazza dell'Esedra, the name indicating the exedra of the Baths of Diocletian (the building on the opposite site of the square). The semicircular porticoed fronts of the palaces on either side of the entrance to the piazza follow the line of the exedra and were built in 1896-1902 by G.Koch.

In the center is the Fontana delle Naiadi (Fountain of the Naiads). Its basin is by Alessandro Guerrieri (1901); four bronze groups of nymphs (a nymph of lakes, a nymph of rivers, a nymph of oceans and a nymph of underground waters) and the central Glaucus are by M.Rutelli (1901-1911). This fountain should be considered as the "mostra" (show) of water Acqua Marcia brought to Rome with the name "Acqua Pia Antica Marcia" by Pius IX and unveiled on September 10, 1870.