This is the residence of the President of the Republic of Italy. It was designed by a number of well known architects and built over a span of two centuries.
In the mid 16th century, the Farnese Pope Paul III was guest at the Villa Carafa on the Quirinal Hill and, while there, he grew to like this part of Rome
This hill, so close the Campidoglio the heart of secular Rome, was secluded amidst greenery and freshened by Rome's westerly breezes, an ideal site he thought for the pope's summer residence.
After Paul, Pope Gregory XIII commissioned Mascherino to build the residence, incorporating the Villa Carafa- D'Este into it. Later on, Sixtus V acquired the entire zone and had Domenico Fontana complete the building, more or less as it stands today.
Maderno and Bernini carried out some modifications for Pope Paul V at the start of the 17th century, constructing the entrance portal and the Benediction Loggia.
Forced by the Thirty Years' War to rethink the Papal Power's defenses, Urban VIII decided to have the whole building fortified and constructed the small tower.
However, these fortifications were not able to save Pius VII who was arrested by the French when they captured the palace. It became Napoleon's Imperial Residence until 1814, when the Popes were able to return.
All the conclaves of the 19th century were held in this palace and Pope Pius IX was in residence here in 1870 when Rome became Italy's capital.
In accordance with King Vittorio Emanuele II's wishes, this palace eventually became the Royal family's residence and remained so until the 1946 referendum made Italy a republic.