When Pope Alexander VII Chigi decided in 1656 to widen St. Peter Square, the Congregation of the Construction convened the famous Gian Lorenzo Bernini, who had already arranged the interior of the Church. The first plan, introduced by the artist after only three weeks, was found meager; the Congregation and the Pope himself insisted for a wider and oval development of the square.

So he matured, not without thoughts and small changes, the plan of organization of the area that had to receive the faithful of the Christianity, as we see it today.

The Bernini's operation had to consider several factors: the great dimensions of the facade and the cupola, the particular liturgical requirements of the papal ceremonial, the city planning connections.

According to the explicit indication of the Pope, Bernini chose the human oval shape for the colonnade to enclose in a hug the space of containment of faithful. Moreover the oval wings balanced harmonically the proportion between the huge basilica body and the square, in order to 'demonstrate to receive all maternally'.

Two problems emerged: the connection between the two semicircular wings (to whom Bernini had added in the plan a third 'straight' wing which closed the oval) and the wide porch of the church; and the joining between the 'oval' and the 'straight' square in front of it.

Bernini solved the question planning two 'wings' or 'corridors' that are the lateral closed buildings whose external decorative frame continues the pattern of the colonnade through twins jutting pillars among the rectangular windows.

Some scholars have noticed the difficulty in combining the curve wings with the straight one because of trapezial pillars. It is evident, indeed, how the longitudinal bodies diverge from the facade and converge on the square.