Two bollards (two half-column) are placed in front of the entrance of Palazzo Pamphili. These stones have a curious story. Around 400 A.D. these pillars belonged to the previous Basilica of San Pietro built by Emperor Constantine. Later, when the church was renovated, the columns of the structure were considered as waste but Donna Olimpia decided to save 2 of them. She even commissioned the carving of a dove with the olive branch in its beack, symbol of Pope Pamphili, the same bird that you can see on the top of the obelisk in Fontana dei Fiumi.