Altar in the Confessio, a 17th-century sunken chapel that can be seen from the crypt and in the main church, next to the baldacchino. This is the closest the general public can get to the tomb of St. Peter, which is on the other side of the wall with the niche at the end of the chapel. It can only be seen in the special Scavi tour of the ancient necropolis. The niche contains a silver coffer with fabrics (each known as a "pallium") woven from the wool of lambs blessed on the feast of St. Agnes (Jan 21) and given to patriarchs and metropolitans as a reminder of the Church's unity. Behind the coffer is an early 8th-century Byzantine mosaic of Christ, placed here by Pope Leo III (795-816). In his left hand Christ holds a Bible open at the Gospel of John, which bears the Latin inscription, "I am the way the truth and the life, the one who believes in me shall live."