Gian Lorenzo Bernini designed the square almost 100 years later, including the massive Tuscan colonnades,[1][2] four columns deep, which embrace visitors in "the maternal arms of Mother Church".

The massed accretions of the Vatican Palace crowded the space to the right of the basilica's façade; the structures needed to be masked without obscuring the papal apartments.

The trapezoidal shape of the piazza, which creates a heightened perspective for a visitor leaving the basilica and has been praised as a masterstroke of Baroque theater (illustration, below right), is largely a product of site constraints.

According to the Lateran Treaty the area of St. Peter's Square is subject to the authority of Italian police for crowd control even though it is a part of the Vatican state.

The ovato tondo's long axis, parallel to the basilica's façade, creates a pause in the sequence of forward movements that is characteristic of a Baroque monumental approach.

It was moved to its current site in 1586 by the engineer-architect Domenico Fontana under the direction of Pope Sixtus V; the engineering feat of re-erecting its vast weight was memorialized in a suite of engravings.

Though Bernini had no influence in the erection of the obelisk, he did use it as the centerpiece of his magnificent piazza, and added the Chigi arms to the top in honor of his patron, Alexander VII.