Under Pope Paul V, Carlo Maderno began designing and building a new basilica façade (a key step in reshaping the forecourt and processional approach). The first stone was laid in early 1608 as the project moved from design to construction.
The Fontana dell’Acqua Paola (“Il Fontanone”) was built in 1612 to mark the terminus of the restored Acqua Paola. This water supply supported major fountain displays in the Vatican area, including the later Baroque staging of St. Peter’s Square.
Maderno’s façade work reached a major completion point in 1612, establishing the monumental backdrop that later urban-design interventions (notably Bernini’s trapezoid and oval) were designed to frame and visually correct.
Commissioned by Pope Paul V, Carlo Maderno reworked the existing piazza fountain into a new Baroque composition (octagonal base and revised basins). This became the model that would later be echoed to create symmetry in Bernini’s square.
Pope Alexander VII formally engaged Gian Lorenzo Bernini to develop designs for a comprehensive reordering of the space before St. Peter’s—an urban-design project intended to manage crowds, ceremonies, and the basilica’s monumental perspective.
After months of rejected proposals and revisions, Bernini received approval to proceed (March 1657). This cleared the way for execution of the colonnaded “arms” that would define the square’s enclosing geometry.
Consensus on the final colonnade solution was reached between spring 1659 and spring 1660, stabilizing the project’s geometry, alignments, and architectural language for construction and completion.
Bernini substantially reworked the Scala Regia to create a more ceremonially powerful connection between the Apostolic Palace and St. Peter’s, using forced perspective and an architecturally staged approach route within the Vatican’s urban-ritual system.
The remodeling campaign on the Scala Regia concluded by 1666, completing a key piece of ceremonial circulation that complemented the broader re-planning of St. Peter’s Square under Alexander VII.
After roughly eleven years of work under Alexander VII, Bernini’s colonnade enclosing the oval and framing the trapezoidal approach was completed in 1667—cementing one of the era’s most influential urban spaces.
To fit the new spatial axes, Bernini rebuilt Maderno’s earlier fountain with small variations and shifted it forward to align with the obelisk and the square’s main axis—integrating preexisting elements into the new urban composition.
St. Peter's Square and Vatican urban projects (1606–1667)
