Towards the back of the nave you can enter two large, densely decorated chapels with domes, which contain papal tombs and other prized sculptures. The right one was built in the second half of the sixteenth century and is called the "Sistine Chapel" because it contains the tomb of Pope Sixtus V, but don't confuse it with the much more famous Sistine Chapel in the Vatican! The group of marble statues you see under the altar is a 14th-century work by Arnolfo di Cambio that depicts The Adoration of the Magi.
