When Emperor Charles V visited Rome in 1536, Pope Paul III Farnese was so embarrased by the muddy state of the Capitol that he asked Michelangelo to draw up plans for repaving the piazza, and for renovating the façades of the Palazzo dei Conservatori and Palazzo Senatorio.
Michelangelo proposed adding the Palazzo Nuovo to form a piazza in the shape of a trapezium, embellished with Classical sculptures chosen for their relevance to Rome. Building started in 1546 but progressed so slowly that Michelangelo only lived to oversee the double flight of steps at the entrance of Palazzo Senatorio.
The piazza was completed in the 17th century, the design remaining largely faithful to the original. Pilasters two storeys high and balustrades interspersed with statues link the buildings thematically.