Built around 1540 for Cardinal Gerolamo Capo di Ferro, Palazzo Spada was purchased by the eponymous Cardinal Spada in 1632, who then hired Borromini to restore it—most of what you see today dates from that period. Its richly ornate facade, covered in high-relief stucco decorations in the Mannerist style, is the finest of any building from 16th-century Rome. The State Rooms are closed (the Italian Council of State still meets here), but the richly decorated courtyard and corridor, Borromini’s masterful illusion of perspective (la prospettiva di Borromini), and the four rooms of the Galleria Spada are open to the public. Inside you will find some absorbing paintings, such as the “Portrait of Cardinale Bernardino Spada” by Guido Reni, and Titian’s “Portrait of a Violinist,” plus minor works from Caravaggio, Parmigianino, Pietro Testa, and Giambattista Gaulli.