The statue of St Longinus (1629-38) is the work of Gian Lorenzo Bernini (1598-1680).
Longinus is the name given (in the apocryphal Gospel of Nicodemus) to the unnamed Roman centurion who pierced the side of Christ with his lance. St. Luke writes that when Christ died the centurion, 'glorified God, saying, Certainly this was a righteous man' (Luke 23:47, KJV). Longinus is believed to have later converted to Christianity.
What was believed to be the metal tip of the Holy Lance of Longinus was donated to Pope Innocent VIII (r. 1484-92) in 1492.