Restoration of the Sistine Chapel frescoes between 1980 and 1994. This most recent restoration had a profound effect on art lovers and historians, as colours and details that had not been seen for centuries were revealed. It has been claimed that as a result "Every book on Michelangelo will have to be rewritten". Others, such as the art historian James Beck of ArtWatch International, have been extremely critical of the restoration, saying that the restorers have not realised the true intentions of the artist. This is the subject of continuing debate. The frescoes on the ceiling of the Sistine Chapel had a number of interventions prior
Sistine Chapel congregations. These included the Christmas Day and Easter masses, at which the Pope himself was the celebrant. The other 27 masses could be held in a smaller, less public space, for which the "Cappella Maggiore" was used before it was rebuilt on the same site as the Sistine Chapel. The "Cappella Maggiore" derived its name, the Greater Chapel, from the fact that there was another chapel also in use by the Pope and his retinue for daily worship. At the time of Pope Sixtus IV, this was the Chapel of Pope Nicholas V, which had been decorated by Fra Angelico.