Palazzo Colonna. The Palazzo Colonna is a palatial block of buildings in central Rome, Italy, at the base of the Quirinal Hill, and adjacent to the church of Santi Apostoli. It is built in part over the ruins of an old Roman serapeum, and it has belonged to the prominent Colonna family for over twenty generations. The first part of the palace dates from the 13th century, and tradition holds that the building hosted Dante during his visit to Rome. The first documentary mention notes that the property hosted Cardinals Giovanni and Giacomo Colonna in the 13th century. It was also home to Cardinal Oddone Colonna before he ascended to the papacy as Pope Martin V in 1417. With his passing, the palace was sacked during feuds, and the main property passed into the hands of the Della Rovere family. It returned to the Colonna family when Marcantonio I Colonna married Lucrezia Gara Franciotti Della Rovere, the niece of Pope Julius II. The Colonna family's alliance to the Habsburg power likely protected the palace from looting during the Sack of Rome. Starting with Filippo Colonna, many changes have refurbished and create a unitary complex around a central garden. Architects including Girolamo Rainaldi and Paolo Marucelli labored on specific projects. Only in the 17th and 18th centuries were the main facades completed, one facing Piazza SS. Apostoli and the other facing Via della Pilotta. Much of this design was completed by Antonio del Grande and Girolamo Fontana. In the 18th century, the long low facade designed by Nicola Michetti, with later additions by Paolo Posi with taller corner blocks, was constructed and recalls earlier structures resembling a fortification. The main gallery and the masterful Colonna art collection was acquired after 1650 by both the cardinal Girolamo I Colonna and his nephew, the Connestabile Lorenzo Onofrio Colonna.