The man who most consider the greatestsculptor of the 17thcentury, Gian Lorenzo Bernini (1598-1680), redesignedthe squarefrom 1656 to 1667, under the direction ofPopeAlexanderVII.
The time of this project coincided with a large Marian trend: in 1661, PopeAlexanderVII declared the Immaculate Conception (though it didn't become a dogma of the church until 1854).