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The Scala Santa, said to be the staircase that Jesus walked up in Pontius Pilate’s Jerusalem palace, was brought to Rome by St Helena in the 4th century. Pilgrims consider it sacred and climb it on their knees, saying a prayer on each of the 28 steps. At the top, behind iron grating, is the richly decorated Sancta Sanctorum (Holy of Holies), formerly the pope’s private chapel.

Behind the sanctuary building you’ll see a cut-off cross-section of a building adorned with a showy gold mosaic. This is the Triclinium Leoninum, an 18th-century reconstruction of a wall from the original Palazzo Laterano.