Scala Santa & Sancta Sanctorum

Lonely Planet review

Over the road from the Basilica di San Giovanni, this is one of the few religious sites in the city with a genuinely spiritual atmosphere. The staircase is said to be the one Jesus walked up in Pontius Pilate's palace in Jerusalem. Brought to Rome by St Helena in the 4th century, it is considered so sacred that you can only climb it on your knees, saying a prayer on each of the 28 steps. Indulgence is granted to pilgrims on Fridays in Lent.

There was no indulgence, however, for Martin Luther who, in 1510, decided halfway up the stairs that he didn't believe in the divinity of relics and promptly turned round and walked out. On his return to Germany he further irritated the Catholic Church by starting the Reformation.

To protect the stairs, wooden boards have been used to cover them, but they are still said to occasionally bleed through the slats.

At the top of the stairs is the Sancta Sanctorum (Holy of Holies), once the pope's private chapel. A spectacular sight, it's richly decorated: the vaulted ceiling is covered with 13th-century mosaics; the marble floor is by Cosmati; and there are 13th-century frescoes depicting the apostles and saints. In June 2007, after a 13-month restoration project, a series of 16th-century frescoes by the Flemish artist Paul Bril were also revealed.