Rome was a major world centre of the Renaissance, second only to Florence, and was profoundly affected by the movement. Among others, a masterpiece of Renaissance architecture in Rome is the Piazza del Campidoglio by Michelangelo. During this period, the great aristocratic families of Rome used to build opulent dwellings as the Palazzo del Quirinale (now seat of the President of the Italian Republic), the Palazzo Venezia, the Palazzo Farnese, the Palazzo Barberini, the Palazzo Chigi (now seat of the Italian Prime Minister), the Palazzo Spada, the Palazzo della Cancelleria, and the Villa Farnesina.