Whenever Alessandra Zarelli, a restorer at the Vatican Museums, works on a masterpiece by an artist such as Michelangelo, she steadies her heart so her mind can concentrate on the task at hand. "The emotion of working on something like a Michelangelo is truly indescribable," said Zarelli, 56, who helped restore a fresco by the Renaissance master in the Pauline Chapel. She is one of about 36 members of an elite team at the Vatican Museums' restoration lab for paintings and wood.