The Centre of the Roman Catholic faith, St. Peter's draws pilgrims from all over the world. Few are disappointed when they enter the sumptuously decorated basilica beneath Michelangelo's vast dome. A shrine was erected on the site of St. Peter's tomb in the 2and century and the first great basilica, ordered by the Emperor Costantine, was completed around AD 349.
By the 15th century it was falling down, so in 1506 Pope Julius II laid the first stone of a new church. It took more than a century to build and all the great architects of the Roman Renaissance and Baroque had a hand in its design.
In 1626 Urban VIII commissioned Bernini to continue the work, especially the restructuring of the façade. Then, after falling from favor under Innocent X, he was brought back by Alexander VII (1655-67) to design the new square in front of the basilica.
Maderno's façade needed to be given greater breadth; the irregular buildings surrounding the square in 1586 had to be hidden; the obelisk set up in the square in 1586 had to be taken into account; and it was also necessary to enable a larger crowd to see the Pope during the Urbi et Orbi blessing.
Bernini'solution was to design a piazza in the form of an ellipse, bordered by a quadruple colonnade forming a portico wide enough to let a carriage pass. The foci of the are indicated by marble disk on each side of the two fountains; standing on either of these disks you can see only one row of columns, instead of four.
Two wings link the colonnades to the basilica: the one on the right end at the Scala Regia, the one on the left at the Arco delle Campane.