 It is penetrated visually from every direction, and is visually linked to the "Cathedra Petri" in the apse behind it and to the four piers containing large statues that are at each diagonal.As part of the scheme for the central space of the church, Bernini had the huge piers, begun by Bramante and completed by Michelangelo, hollowed out into niches, and had staircases made inside them, leading to four balconies.There was much dismay from those who thought that the dome might fall, but it did not.