The building of the Scala Sancta houses what is traditionally indicated as the staircase in Pontius Pilate's praetorium, stained with the blood of Jesus. The history of this location recalls that of the so-called Patriarchium, founded by Pope Sylvester I, pontiff under Emperor Constantine. The Patriarchium was completed by the year 324, when Pope Sylvester I declared it Domus Dei (House of God) together with the adjacent Basilica. In the centuries that followed, the residence of the bishop of Rome became increasingly large and richly adorned, also for the holding of the papal ceremonies that were gradually being codified within it. It consisted of reception rooms, chapels and archives joined together by courtyards and internal corridors that together formed the papal residence that would remain so until the Avignon exile. In the Patriarchate, apart from the Basilica itself, there was a portico connecting the palace with the Scala Sancta. Under Pope Sixtus V, to whom we owe many interventions in the city of Rome, the Scala Sancta was moved in order to be the path leading to the chapel of the Sancta Sanctorum.
However, given the precious nature of the staircase, the series of paintings that now frames it was realized before the staircase was moved, so that the painters would not step on the sacred space. The cycle of frescoes, created under the guidance of Cesare Nebbia and Giovanni Guerra, represents the scenes of the Passion of Christ. The Scala Sancta is made up of twenty-eight white marble steps, covered with maple word during the pontificate of Pope Innocent XIII, in order to prevent wear.
At the side of the Scala Sancta, which can still only be ascended on one’s knees, two other stairways lead up to the chapel of the Sancta Sanctorum. The cycle of frescoes decorating the walls of these minor stairways features scenes from the Old Testament.