The piazza has been a monumental open space since Antiquity; the temple of Marcus Aurelius stood on the site of Palazzo Wedekind (TCI).
Fountain
The fountain in the piazza (1577) was commissioned by Pope Gregory XIII from Giacomo Della Porta who was assisted by Rocco De Rossi. In 1830, it was restored and had two sets of dolphins side by side, with tails entwined, sculpted by Achille Stocchi, set at either end of the long basin. The central sculpture was then substituted with a smaller sculpture and spray.[1]