It was built in Quirinal Square about in 1584 according to Pope Gregorio XIII's will. To give the palace its current shape, many great artists collaborated; some of them are: Domenico Fontana who designed the façade, Carlo Maderno who designed the great chapel, Flaminio Ponzio, Gian Lorenzo Bernini and Alessandro Fuga. The building was definitively completed in the XVIII century, under the pontificate of Pope Clemente XII Corsini.
It is a grandiose building, but its architectonic structure hasn't got an exceptional value in spite of the great artists who made it. Its façade has a very interesting decorative element: the beautiful portal realized in 1615 by Carlo Maderno and overhung by the Loggia of Blessing realized in 1638 by Bernini. Inside, you can see a wide courtyard, at the end of which, a high clock tower rises. The wide and very numerous rooms were decorated with remarkable frescoes by several painters. In particular, you can admire the interesting "Cappella dell'Annunciata" with frescoes by Guido Reni. Besides, there is the magnificent garden which dates back to the beginning of the XVIII century. In it, the peculiar "Fontana dell'Organo" is very beautiful.