Rebuilt in 1586, the Lateran Palace was the popes’ residence until they left for Avignon. Of the medieval building, the Scala sancta (a staircase traditionally identified with the steps climbed by Christ in Pontius Pilate’s palace) survives; devout visitors scale these stairs on their knees. At the top is the private papal chapel, called the “Sancta Sanctorum” on account of the precious relics kept there.