The use of the Benedictine arrangement on the (relatively) newly replaced Altar of the Chair.
As an aside, for Masses such as these, the Altar of the Chair would be the prime spot within the Vatican Basilica to give clear witness to the continuing applicability of the use of ad orientem liturgicum (as it was expressed within the majority of Catholic churches and chapels that is, and as differed from the tradition as it was expressed upon the high altars of the Roman basilicas).
For the occasion, the Pope wore a splendid red Roman cope.
