City centre and centre of political life of Rome, the square is surrounded by famous buildings: the Palazzo Chigi (on the right, with the colonnade behind) seat of the Cabinet Office since 1961; on the left is the Palazzo Ferraioli, already Del Bufalo, Aldobrandini and Niccolini. 

To the right is the small church S. Bartolomeo ai Bergamaschi, aka Santa Maria della Pietà, founded in 1561 as chapel for the Ospedale dei Pazzi; opposite is the Palazzo Wedekind, embellished by 16 gorgeous ionic columns from Veii and back is the building of Galleria Colonna. 

At the centre of the square is the fountain by Giacomo Della Porta and Marc Aurelius’ Column (176-193) decorated with bas-reliefs to celebrate the triumph of the emperor upon the Marcomanni, the Quadi and the Sarmatians.