The Piazza San Pietro, otherwise known as the St. Peter's Piazza was commissioned by Pope Alexander VII, Bernini designed and completed the construction in under five years. I like to think of the Pope Alexander VII and Bernini having a tight relationship and perhaps the Pope as somewhat of a fanboy, since Bernini was his favorite architect of the period.

The Pope explained his desire for the project that would later become the smallest country in the world - Vatican City. The design of the Piazza was based off St. Peter's Basilica, which stands as one of the most iconic Christians in the world. The goal was to create a sanctuary, safe from the outside harms of the world. 

When discussing the teams aspirations Bernini once said, "considering that Saint Peter's is almost the matrix of all the churches, its portico had to give an open-armed, maternal welcome to all Catholics, confirming their faith; to heretics, reconciling them with the Church and ti the infidels, enlightening them about the true faith." Creating such an experience took  tedious planning, as Bernini had to work around preexisting architecture. Despite these difficulties, Bernini's genius is responsible for the construction of what is now regarded as an extremely progressive and religiously stimulating piece of architecture.