At the base of the ancient Egyptian obelisk, which graces the centre of the piazza, stands the Fontana dei Quattro Leoni (Fountain of the Four Lions), 1828, which was designed by the Roman architect Giuseppe Valadier (1762-1830). The fountain actually takes the form of four mini-fountains, each comprising a marble lion sitting on a stepped plinth.
Fountain of Neptune
On the west side of the piazza is the Fontana del Nettuno (Fountain of Neptune), 1818-21, and on the east the Fontana della Dea di Roma (Fountain of the Goddess of Rome), 1818-21, both the work of the Roman sculptor Giovanni Ceccarini (c.1790-1861).