Bernini was named the chief architect of St. Peter’s in 1629, and retained that position for several decades. His design of the piazza was intended to create the impression that the church was a person holding open their arms to welcome visitors. This was accomplished with an oval and then a trapezoid framed by colonnades made up of about 300 columns. The longest axis of the oval is perpendicular to the axis you walk in on. The obelisk and 2 fountains are also on this axis. Bernini planned the 96 statues of saints and martyrs that over look the piazza from on top of the colonnade. The design certainly makes for a dramatic approach up to the church.