For its solemnity and its majestic proportions the palace is one of the most sumptuous of the city. It is called “harpsichord” for its shape and its “keyboard” should be the short side with two balconies looking towards the Tiber. Began in 1560, probably after a design by Vignola, it was completed by Flaminio Ponzio and Carlo Maderno in 1614. 

Over the portal of the long side, which has two Doric columns supporting a balcony, is a large coat of arms of the family. The second portal, that has the same shape of the previous but has no coat of arms, opens to the side of the piazza. This is the entrance to a large court with a double order of columns and at the end is the extraordinary “bath of Venus”, a nymphaeum with statues, climbers and fountains. 

For a long time the ground floor housed the collection of paintings that has been moved to Villa Borghese in 1891.